Lipid-anchored protein

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Lipid membrane with various proteins 0303 Lipid Bilayer With Various Components.jpg
Lipid membrane with various proteins

Lipid-anchored proteins (also known as lipid-linked proteins) are proteins located on the surface of the cell membrane [ of what? ] that are covalently attached to lipids embedded within the cell membrane. These proteins insert and assume a place in the bilayer structure of the membrane alongside the similar fatty acid tails. The lipid-anchored protein can be located on either side of the cell membrane. Thus, the lipid serves to anchor the protein to the cell membrane. [1] [2] They are a type of proteolipids.

Contents

The lipid groups play a role in protein interaction and can contribute to the function of the protein to which it is attached. [2] Furthermore, the lipid serves as a mediator of membrane associations or as a determinant for specific protein-protein interactions. [3] For example, lipid groups can play an important role in increasing molecular hydrophobicity. This allows for the interaction of proteins with cellular membranes and protein domains. [4] In a dynamic role[ clarification needed ], lipidation can sequester a protein away from its substrate to inactivate the protein and then activate it by substrate presentation.

Overall, there are three main types of lipid-anchored proteins which include prenylated proteins, fatty acylated proteins and glycosylphosphatidylinositol-linked proteins (GPI). [2] [5] A protein can have multiple lipid groups covalently attached to it, but[ clarification needed ] the site where the lipids bind to the protein depends both on the lipid group and protein. [2]

Prenylated proteins

Isoprene unit Isoprene.svg
Isoprene unit

Prenylated proteins are proteins with covalently attached hydrophobic isoprene polymers (i.e. branched five-carbon hydrocarbon [6] ) at cysteine residues of the protein. [2] [3] More specifically, these isoprenoid groups, usually farnesyl (15-carbon) and geranylgeranyl (20-carbon) are attached to the protein via thioether linkages at cysteine residues near the C terminal of the protein. [3] [4] This prenylation of lipid chains to proteins facilitate their interaction with the cell membrane. [1]

Caax Box Caaxbox.JPG
Caax Box

The prenylation motif “CaaX box” is the most common prenylation site in proteins, that is, the site where farnesyl or geranylgeranyl covalently attach. [2] [3] In the CaaX box sequence, the C represents the cysteine that is prenylated, the A represents any aliphatic amino acid and the X determines the type of prenylation that will occur. If the X is an Ala, Met, Ser or Gln the protein will be farnesylated via the farnesyltransferase enzyme and if the X is a Leu then the protein will be geranylgeranylated via the geranylgeranyltransferase I enzyme. [3] [4] Both of these enzymes are similar with each containing two subunits. [7]

Roles and function

Prenylation chains (e.g. geranyl pyrophosphate) Synthesis of geranyl pyrophosphate.png
Prenylation chains (e.g. geranyl pyrophosphate)

Prenylated proteins are particularly important for eukaryotic cell growth, differentiation and morphology. [7] Furthermore, protein prenylation is a reversible post-translational modification to the cell membrane. This dynamic interaction of prenylated proteins with the cell membrane is important for their signalling functions and is often deregulated in disease processes such as cancer. [8] More specifically, Ras is the protein that undergoes prenylation via farnesyltransferase and when it is switched on it can turn on genes involved in cell growth and differentiation. Thus overactiving Ras signalling can lead to cancer. [9] An understanding of these prenylated proteins and their mechanisms have been important for the drug development efforts in combating cancer. [10] Other prenylated proteins include members of the Rab and Rho families as well as lamins. [7]

Some important prenylation chains that are involved in the HMG-CoA reductase metabolic pathway [1] are geranylgeraniol, farnesol and dolichol. These isoprene polymers (e.g. geranyl pyrophosphate and farnesyl pyrophosphate) are involved in the condensations via enzymes such as prenyltransferase that eventually cyclizes to form cholesterol. [2]

Fatty acylated proteins

Fatty acylated proteins are proteins that have been post-translationally modified to include the covalent attachment of fatty acids at certain amino acid residues. [11] [12] The most common fatty acids that are covalently attached to the protein are the saturated myristic (14-carbon) acid and palmitic acid (16-carbon). Proteins can be modified to contain either one or both of these fatty acids. [11]

Myristoylation Myristoylation.pdf
Myristoylation

N-myristoylation

N-myristoylation (i.e. attachment of myristic acid) is generally an irreversible protein modification that typically occurs during protein synthesis [11] [13] in which the myrisitc acid is attached to the α-amino group of an N-terminal glycine residue through an amide linkage. [2] [12] This reaction is facilitated by N-myristoyltransferase . These proteins usually begin with a Met-Gly sequence and with either a serine or threonine at position 5. [11] Proteins that have been myristoylated are involved in signal transduction cascade, protein-protein interactions and in mechanisms that regulate protein targeting and function. [13] An example in which the myristoylation of a protein is important is in apoptosis, programmed cell death. After the protein BH3 interacting-domain death agonist (Bid) has been myristoylated, it targets the protein to move to the mitochondrial membrane to release cytochrome c, which then ultimately leads to cell death. [14] Other proteins that are myristoylated and involved in the regulation of apoptosis are actin and gelsolin.

S-palmitoylation

Palmitoylation Palmitoylation.png
Palmitoylation

S-palmitoylation (i.e. attachment of palmitic acid) is a reversible protein modification in which a palmitic acid is attached to a specific cysteine residue via thioester linkage. [2] [11] The term S-acylation can also be used when other medium and long fatty acids chains are also attached to palmitoylated proteins. No consensus sequence for protein palmitoylation has been identified. [11] Palmitoylated proteins are mainly found on the cytoplasmic side of the plasma membrane where they play a role in transmembrane signaling. The palmitoyl group can be removed by palmitoyl thioesterases. It is believed that this reverse palmitoylation may regulate the interaction of the protein with the membrane and thus have a role in signaling processes. [2] Furthermore, this allows for the regulation of protein subcellular localization, stability and trafficking. [15] An example in which palmitoylation of a protein plays a role in cell signaling pathways is in the clustering of proteins in the synapse. When the postsynaptic density protein 95 (PSD-95) is palmitoylated, it is restricted to the membrane and allows it to bind to and cluster ion channels in the postsynaptic membrane. Thus, palmitoylation can play a role in the regulation of neurotransmitter release. [16]

Palmitoylation mediates the affinity of a protein for lipid rafts and facilitates the clustering of proteins. [17] The clustering can increase the proximity of two molecules. Alternatively, clustering can sequester a protein away from a substrate. For example, palmitoylation of phospholipase D (PLD) sequesters the enzyme away from its substrate phosphatidylcholine. When cholesterol levels decrease or PIP2 levels increase the palmitate mediated localization is disrupted, the enzyme trafficks to PIP2 where it encounters its substrate and is active by substrate presentation. [18] [19] [20]

GPI proteins

Structure of the glycophosphatidylinositol anchor in the plasma membrane of a eukaryotic cell Glycophosphatidylinositol anchor.tif
Structure of the glycophosphatidylinositol anchor in the plasma membrane of a eukaryotic cell

Glycosylphosphatidylinositol-anchored proteins (GPI-anchored proteins) are attached to a GPI complex molecular group via an amide linkage to the protein's C-terminal carboxyl group. [21] This GPI complex consists of several main components that are all interconnected: a phosphoethanolamine, a linear tetrasaccharide (composed of three mannose and a glucosaminyl) and a phosphatidylinositol. [22] The phosphatidylinositol group is glycosidically linked to the non-N-acetylated glucosamine of the tetrasaccharide. A phosphodiester bond is then formed between the mannose at the nonreducing end (of the tetrasaccaride) and the phosphoethanolamine. The phosphoethanolamine is then amide linked to the C-terminal of the carboxyl group of the respective protein. [2] The GPI attachment occurs through the action of GPI-transamidase complex. [22] The fatty acid chains of the phosphatidylinositol are inserted into the membrane and thus are what anchor the protein to the membrane. [23] These proteins are only located on the exterior surface of the plasma membrane. [2]

Roles and function

The sugar residues in the tetrasaccaride and the fatty acid residues in the phosphatidylinositol group vary depending on the protein. [2] This great diversity is what allows the GPI proteins to have a wide range of functions including acting as hydrolytic enzymes, adhesion molecule, receptors, protease inhibitor and complement regulatory proteins. [24] Furthermore, GPI proteins play an important in embryogenesis, development, neurogenesis, the immune system and fertilization. [21] More specifically, the GPI protein IZUMO1R (also named JUNO after the Roman goddess of fertility) on the egg plasma has an essential role in sperm-egg fusion. Releasing the IZUMO1R (JUNO) GPI protein from the egg plasma membrane does not allow for sperm to fuse with the egg and it is suggested that this mechanism may contribute to the polyspermy block at the plasma membrane in eggs. [25] Other roles that GPI modification allows for is in the association with membrane microdomains, transient homodimerization or in apical sorting in polarized cells. [21]

Related Research Articles

<span class="mw-page-title-main">Protein primary structure</span> Linear sequence of amino acids in a peptide or protein

Protein primary structure is the linear sequence of amino acids in a peptide or protein. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end. Protein biosynthesis is most commonly performed by ribosomes in cells. Peptides can also be synthesized in the laboratory. Protein primary structures can be directly sequenced, or inferred from DNA sequences.

<span class="mw-page-title-main">Post-translational modification</span> Biological processes

Post-translational modification (PTM) is the covalent process of changing proteins following protein biosynthesis. PTMs may involve enzymes or occur spontaneously. Proteins are created by ribosomes translating mRNA into polypeptide chains, which may then change to form the mature protein product. PTMs are important components in cell signalling, as for example when prohormones are converted to hormones.

<span class="mw-page-title-main">Peripheral membrane protein</span> Membrane proteins that adhere temporarily to membranes with which they are associated

Peripheral membrane proteins, or extrinsic membrane proteins, are membrane proteins that adhere only temporarily to the biological membrane with which they are associated. These proteins attach to integral membrane proteins, or penetrate the peripheral regions of the lipid bilayer. The regulatory protein subunits of many ion channels and transmembrane receptors, for example, may be defined as peripheral membrane proteins. In contrast to integral membrane proteins, peripheral membrane proteins tend to collect in the water-soluble component, or fraction, of all the proteins extracted during a protein purification procedure. Proteins with GPI anchors are an exception to this rule and can have purification properties similar to those of integral membrane proteins.

Glycosylphosphatidylinositol or glycophosphatidylinositol (GPI) is a phosphoglyceride that can be attached to the C-terminus of a protein during posttranslational modification. The resulting GPI-anchored proteins play key roles in a wide variety of biological processes. GPI is composed of a phosphatidylinositol group linked through a carbohydrate-containing linker and via an ethanolamine phosphate (EtNP) bridge to the C-terminal amino acid of a mature protein. The two fatty acids within the hydrophobic phosphatidyl-inositol group anchor the protein to the cell membrane.

The C-terminus is the end of an amino acid chain, terminated by a free carboxyl group (-COOH). When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus. The convention for writing peptide sequences is to put the C-terminal end on the right and write the sequence from N- to C-terminus.

In chemistry, acylation is a broad class of chemical reactions in which an acyl group is added to a substrate. The compound providing the acyl group is called the acylating agent. The substrate to be acylated and the product include the following:

<span class="mw-page-title-main">Prenylation</span> Addition of hydrophobic moieties to proteins or other biomolecules

Prenylation is the addition of hydrophobic molecules to a protein or a biomolecule. It is usually assumed that prenyl groups (3-methylbut-2-en-1-yl) facilitate attachment to cell membranes, similar to lipid anchors like the GPI anchor, though direct evidence of this has not been observed. Prenyl groups have been shown to be important for protein–protein binding through specialized prenyl-binding domains.

<span class="mw-page-title-main">Glycolipid</span> Class of chemical compounds

Glycolipids are lipids with a carbohydrate attached by a glycosidic (covalent) bond. Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the connections that allow cells to connect to one another to form tissues. Glycolipids are found on the surface of all eukaryotic cell membranes, where they extend from the phospholipid bilayer into the extracellular environment.

Phosphatidic acids are anionic phospholipids important to cell signaling and direct activation of lipid-gated ion channels. Hydrolysis of phosphatidic acid gives rise to one molecule each of glycerol and phosphoric acid and two molecules of fatty acids. They constitute about 0.25% of phospholipids in the bilayer.

<span class="mw-page-title-main">Myristoylation</span>

Myristoylation is a lipidation modification where a myristoyl group, derived from myristic acid, is covalently attached by an amide bond to the alpha-amino group of an N-terminal glycine residue. Myristic acid is a 14-carbon saturated fatty acid (14:0) with the systematic name of n-tetradecanoic acid. This modification can be added either co-translationally or post-translationally. N-myristoyltransferase (NMT) catalyzes the myristic acid addition reaction in the cytoplasm of cells. This lipidation event is the most common type of fatty acylation and is present in many organisms, including animals, plants, fungi, protozoans and viruses. Myristoylation allows for weak protein–protein and protein–lipid interactions and plays an essential role in membrane targeting, protein–protein interactions and functions widely in a variety of signal transduction pathways.

Phospholipase D (EC 3.1.4.4, lipophosphodiesterase II, lecithinase D, choline phosphatase, PLD; systematic name phosphatidylcholine phosphatidohydrolase) is an enzyme of the phospholipase superfamily that catalyses the following reaction

Geranylgeranyltransferase type 1 or simply geranylgeranyltransferase is one of the three enzymes in the prenyltransferase group. In specific terms, Geranylgeranyltransferase adds a 20-carbon isoprenoid called a geranylgeranyl group to proteins bearing a CaaX motif: a four-amino acid sequence at the carboxyl terminal of a protein. Geranylgeranyltransferase inhibitors are being investigated as anti-cancer agents.

Chemical modification refers to a number of various processes involving the alteration of the chemical constitution or structure of molecules.

<span class="mw-page-title-main">Palmitoylation</span>

Palmitoylation is the covalent attachment of fatty acids, such as palmitic acid, to cysteine (S-palmitoylation) and less frequently to serine and threonine (O-palmitoylation) residues of proteins, which are typically membrane proteins. The precise function of palmitoylation depends on the particular protein being considered. Palmitoylation enhances the hydrophobicity of proteins and contributes to their membrane association. Palmitoylation also appears to play a significant role in subcellular trafficking of proteins between membrane compartments, as well as in modulating protein–protein interactions. In contrast to prenylation and myristoylation, palmitoylation is usually reversible (because the bond between palmitic acid and protein is often a thioester bond). The reverse reaction in mammalian cells is catalyzed by acyl-protein thioesterases (APTs) in the cytosol and palmitoyl protein thioesterases in lysosomes. Because palmitoylation is a dynamic, post-translational process, it is believed to be employed by the cell to alter the subcellular localization, protein–protein interactions, or binding capacities of a protein.

<span class="mw-page-title-main">GPLD1</span> Protein-coding gene in the species Homo sapiens

Phosphatidylinositol-glycan-specific phospholipase D is an enzyme that in humans is encoded by the GPLD1 gene.

Src kinase family is a family of non-receptor tyrosine kinases that includes nine members: Src, Yes, Fyn, and Fgr, forming the SrcA subfamily, Lck, Hck, Blk, and Lyn in the SrcB subfamily, and Frk in its own subfamily. Frk has homologs in invertebrates such as flies and worms, and Src homologs exist in organisms as diverse as unicellular choanoflagellates, but the SrcA and SrcB subfamilies are specific to vertebrates. Src family kinases contain six conserved domains: a N-terminal myristoylated segment, a SH2 domain, a SH3 domain, a linker region, a tyrosine kinase domain, and C-terminal tail.

<span class="mw-page-title-main">Diglyceride</span> Type of fat derived from glycerol and two fatty acids

A diglyceride, or diacylglycerol (DAG), is a glyceride consisting of two fatty acid chains covalently bonded to a glycerol molecule through ester linkages. Two possible forms exist, 1,2-diacylglycerols and 1,3-diacylglycerols. Diglycerides are natural components of food fats, though minor in comparison to triglycerides. DAGs can act as surfactants and are commonly used as emulsifiers in processed foods. DAG-enriched oil has been investigated extensively as a fat substitute due to its ability to suppress the accumulation of body fat; with total annual sales of approximately USD 200 million in Japan since its introduction in the late 1990s till 2009.

Glypiation is the addition by covalent bonding of a glycosylphosphatidylinositol (GPI) anchor and is a common post-translational modification that localizes proteins to cell membranes. This special kind of glycosylation is widely detected on surface glycoproteins in eukaryotes and some Archaea.

A proteolipid is a protein covalently linked to lipid molecules, which can be fatty acids, isoprenoids or sterols. The process of such a linkage is known as protein lipidation, and falls into the wider category of acylation and post-translational modification. Proteolipids are abundant in brain tissue, and are also present in many other animal and plant tissues. They include ghrelin, a peptide hormone associated with feeding. Many proteolipids are composed of proteins covalenently bound to fatty acid chains, often granting them an interface for interacting with biological membranes. They are not to be confused with lipoproteins, a kind of spherical assembly made up of many molecules of lipids and some apolipoproteins.

Substrate presentation is a biological process that activates a protein. The protein is sequestered away from its substrate and then activated by release and exposure of the protein to its substrate. A substrate is typically the substance on which an enzyme acts but can also be a protein surface to which a ligand binds. The substrate is the material acted upon. In the case of an interaction with an enzyme, the protein or organic substrate typically changes chemical form. Substrate presentation differs from allosteric regulation in that the enzyme need not change its conformation to begin catalysis. Substrate presentation is best described for nanoscopic distances (<100 nm).

References

  1. 1 2 3 Gerald Karp (2009). Cell and Molecular Biology: Concepts and Experiments. John Wiley and Sons. pp. 128–. ISBN   978-0-470-48337-4 . Retrieved 13 November 2010.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 Voet D, Voet JG, Pratt CW (2013). Fundamentals of Biochemistry: Life at the Molecular Level (4th ed.). John Wiley & Sons, Inc. p. 263. ISBN   978-0470-54784-7.
  3. 1 2 3 4 5 Casey PJ, Seabra MC (March 1996). "Protein prenyltransferases". The Journal of Biological Chemistry. 271 (10): 5289–92. doi: 10.1074/jbc.271.10.5289 . PMID   8621375.
  4. 1 2 3 Novelli G, D'Apice MR (September 2012). "Protein farnesylation and disease". Journal of Inherited Metabolic Disease. 35 (5): 917–26. doi:10.1007/s10545-011-9445-y. PMID   22307208. S2CID   11555502.
  5. ↑ Ferguson MA (August 1991). "Lipid anchors on membrane proteins". Current Opinion in Structural Biology. 1 (4): 522–9. doi:10.1016/s0959-440x(05)80072-7.
  6. ↑ isoprene (2003). "Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Ed" . Retrieved 28 November 2015.
  7. 1 2 3 Lane KT, Beese LS (April 2006). "Thematic review series: lipid posttranslational modifications. Structural biology of protein farnesyltransferase and geranylgeranyltransferase type I". Journal of Lipid Research. 47 (4): 681–99. doi: 10.1194/jlr.R600002-JLR200 . PMID   16477080.
  8. ↑ Stein V, Kubala MH, Steen J, Grimmond SM, Alexandrov K (2015-01-01). "Towards the systematic mapping and engineering of the protein prenylation machinery in Saccharomyces cerevisiae". PLOS ONE. 10 (3): e0120716. Bibcode:2015PLoSO..1020716S. doi: 10.1371/journal.pone.0120716 . PMC   4358939 . PMID   25768003.
  9. ↑ Goodsell DS (1999-01-01). "The molecular perspective: the ras oncogene". The Oncologist. 4 (3): 263–4. doi: 10.1634/theoncologist.4-3-263 . PMID   10394594.
  10. ↑ Reuter CW, Morgan MA, Bergmann L (September 2000). "Targeting the Ras signaling pathway: a rational, mechanism-based treatment for hematologic malignancies?". Blood. 96 (5): 1655–69. doi:10.1182/blood.V96.5.1655. PMID   10961860.
  11. 1 2 3 4 5 6 Resh MD (November 2006). "Trafficking and signaling by fatty-acylated and prenylated proteins". Nature Chemical Biology. 2 (11): 584–90. doi:10.1038/nchembio834. PMID   17051234. S2CID   9734759.
  12. 1 2 Wilson JP, Raghavan AS, Yang YY, Charron G, Hang HC (March 2011). "Proteomic analysis of fatty-acylated proteins in mammalian cells with chemical reporters reveals S-acylation of histone H3 variants". Molecular & Cellular Proteomics. 10 (3): M110.001198. doi:10.1074/mcp.M110.001198. PMC   3047146 . PMID   21076176.
  13. 1 2 Farazi TA, Waksman G, Gordon JI (October 2001). "The biology and enzymology of protein N-myristoylation". The Journal of Biological Chemistry. 276 (43): 39501–4. doi: 10.1074/jbc.R100042200 . PMID   11527981.
  14. ↑ Martin DD, Beauchamp E, Berthiaume LG (January 2011). "Post-translational myristoylation: Fat matters in cellular life and death". Biochimie. Bioactive Lipids, Nutrition and Health. 93 (1): 18–31. doi:10.1016/j.biochi.2010.10.018. PMID   21056615.
  15. ↑ Aicart-Ramos C, Valero RA, Rodriguez-Crespo I (December 2011). "Protein palmitoylation and subcellular trafficking". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1808 (12): 2981–94. doi:10.1016/j.bbamem.2011.07.009. PMID   21819967.
  16. ↑ Dityatev, Alexander (2006). El-Husseini, Alaa (ed.). Molecular Mechanisms of Synaptogenesis. New York: Springer. pp. 72–75.
  17. ↑ Levental, I.; Lingwood, D.; Grzybek, M.; Coskun, U.; Simons, K. (3 December 2010). "Palmitoylation regulates raft affinity for the majority of integral raft proteins". Proceedings of the National Academy of Sciences. 107 (51): 22050–22054. Bibcode:2010PNAS..10722050L. doi: 10.1073/pnas.1016184107 . PMC   3009825 . PMID   21131568.
  18. ↑ Petersen, EN; Chung, HW; Nayebosadri, A; Hansen, SB (15 December 2016). "Kinetic disruption of lipid rafts is a mechanosensor for phospholipase D." Nature Communications. 7: 13873. Bibcode:2016NatCo...713873P. doi:10.1038/ncomms13873. PMC   5171650 . PMID   27976674.
  19. ↑ Robinson, CV; Rohacs, T; Hansen, SB (September 2019). "Tools for Understanding Nanoscale Lipid Regulation of Ion Channels". Trends in Biochemical Sciences. 44 (9): 795–806. doi:10.1016/j.tibs.2019.04.001. PMC   6729126 . PMID   31060927.
  20. ↑ Petersen, EN; Pavel, MA; Wang, H; Hansen, SB (28 October 2019). "Disruption of palmitate-mediated localization; a shared pathway of force and anesthetic activation of TREK-1 channels". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1862 (1): 183091. doi: 10.1016/j.bbamem.2019.183091 . PMC   6907892 . PMID   31672538.
  21. 1 2 3 Kinoshita T, Fujita M (January 2016). "Biosynthesis of GPI-anchored proteins: special emphasis on GPI lipid remodeling". Journal of Lipid Research. 57 (1): 6–24. doi:10.1194/jlr.R063313. PMC   4689344 . PMID   26563290.
  22. 1 2 Ikezawa, Hiroh (2002-01-01). "Glycosylphosphatidylinositol (GPI)-Anchored Proteins". Biological and Pharmaceutical Bulletin. 25 (4): 409–417. doi: 10.1248/bpb.25.409 . PMID   11995915.
  23. ↑ Kinoshita T, Fujita M (January 2016). "Biosynthesis of GPI-anchored proteins: special emphasis on GPI lipid remodeling". Journal of Lipid Research. 57 (1): 6–24. doi:10.1194/jlr.R063313. PMC   4689344 . PMID   26563290.
  24. ↑ Kinoshita T (2014). "Biosynthesis and deficiencies of glycosylphosphatidylinositol". Proceedings of the Japan Academy. Series B, Physical and Biological Sciences. 90 (4): 130–43. Bibcode:2014PJAB...90..130K. doi:10.2183/pjab.90.130. PMC   4055706 . PMID   24727937.
  25. ↑ Coonrod SA, Naaby-Hansen S, Shetty J, Shibahara H, Chen M, White JM, Herr JC (March 1999). "Treatment of mouse oocytes with PI-PLC releases 70-kDa (pI 5) and 35- to 45-kDa (pI 5.5) protein clusters from the egg surface and inhibits sperm-oolemma binding and fusion". Developmental Biology. 207 (2): 334–49. doi: 10.1006/dbio.1998.9161 . PMID   10068467.
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