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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.
The plasma membranes of cells contain combinations of glycosphingolipids, cholesterol and protein receptors organized in glycolipoprotein lipid microdomains termed lipid rafts. Their existence in cellular membranes remains controversial. Indeed, Kervin and Overduin imply that lipid rafts are misconstrued protein islands, which they propose form through a proteolipid code. Nonetheless, it has been proposed that they are specialized membrane microdomains which compartmentalize cellular processes by serving as organising centers for the assembly of signaling molecules, allowing a closer interaction of protein receptors and their effectors to promote kinetically favorable interactions necessary for the signal transduction. Lipid rafts influence membrane fluidity and membrane protein trafficking, thereby regulating neurotransmission and receptor trafficking. Lipid rafts are more ordered and tightly packed than the surrounding bilayer, but float freely within the membrane bilayer. Although more common in the cell membrane, lipid rafts have also been reported in other parts of the cell, such as the Golgi apparatus and lysosomes.
Phosphatidylinositol or inositol phospholipid is a biomolecule. It was initially called "inosite" when it was discovered by Léon Maquenne and Johann Joseph von Scherer in the late 19th century. It was discovered in bacteria but later also found in eukaryotes, and was found to be a signaling molecule.
Phosphatidylinositol 4,5-bisphosphate or PtdIns(4,5)P2, also known simply as PIP2 or PI(4,5)P2, is a minor phospholipid component of cell membranes. PtdIns(4,5)P2 is enriched at the plasma membrane where it is a substrate for a number of important signaling proteins. PIP2 also forms lipid clusters that sort proteins.
Hexadimethrine bromide is a cationic polymer with several uses. In research, it is primarily used to increase the efficiency of transduction of certain cells with viruses in cell culture. Hexadimethrine bromide acts by neutralizing the charge repulsion between virions and sialic acid on the cell surface. Use of Polybrene can improve transduction efficiency 100-1000 fold although it can be toxic to some cell types. Polybrene in combination with DMSO shock is used to transfect some cell types such as NIH-3T3 and CHO. It has other uses, including a role in protein sequencing.
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Phospholipase D (EC 3.1.4.4, lipophosphodiesterase II, lecithinase D, choline phosphatase, PLD; systematic name phosphatidylcholine phosphatidohydrolase) is an anesthetic sensitive and mechanosensitive enzyme of the phospholipase superfamily that catalyses the following reaction
Surfactin is a cyclic lipopeptide, commonly used as an antibiotic for its capacity as a surfactant. It is an amphiphile capable of withstanding hydrophilic and hydrophobic environments. The Gram-positive bacterial species Bacillus subtilis produces surfactin for its antibiotic effects against competitors. Surfactin showcases antibacterial, antiviral, antifungal, and hemolytic effects.
David S. Cafiso is an American biochemist and a professor of chemistry at the University of Virginia. His research focuses on membrane proteins and cell signaling, and is primarily supported by grants from the National Institute of Health.
Phosphatidylinositol-4-phosphate is a precursor of phosphatidylinositol (4,5)-bisphosphate. PtdIns4P is prevalent in the membrane of the Golgi apparatus.
Pleckstrins are a family of proteins found in platelets and other cells. The name derives from platelet and leukocyteC kinase substrate and the KSTR string of amino acids. The prototype protein, now called pleckstrin-1, was first identified in 1979 as the major substrate of protein kinase C in platelets. The homolog pleckstrin-2 is more widely expressed in tissues.
Phospholipase D2 is an enzyme that in humans is encoded by the PLD2 gene.
α-Parinaric acid is a conjugated polyunsaturated fatty acid. Discovered by Tsujimoto and Koyanagi in 1933, it contains 18 carbon atoms and 4 conjugated double bonds. The repeating single bond-double bond structure of α-parinaric acid distinguishes it structurally and chemically from the usual "methylene-interrupted" arrangement of polyunsaturated fatty acids that have double-bonds and single bonds separated by a methylene unit (−CH2−). Because of the fluorescent properties conferred by the alternating double bonds, α-parinaric acid is commonly used as a molecular probe in the study of biomembranes.
Phospholipase C (PLC) is a class of membrane-associated enzymes that cleave phospholipids just before the phosphate group (see figure). It is most commonly taken to be synonymous with the human forms of this enzyme, which play an important role in eukaryotic cell physiology, in particular signal transduction pathways. Phospholipase C's role in signal transduction is its cleavage of phosphatidylinositol 4,5-bisphosphate (PIP2) into diacyl glycerol (DAG) and inositol 1,4,5-trisphosphate (IP3), which serve as second messengers. Activators of each PLC vary, but typically include heterotrimeric G protein subunits, protein tyrosine kinases, small G proteins, Ca2+, and phospholipids.
1-Phosphatidylinositol-4,5-bisphosphate phospholipase beta-1 is an enzyme that in humans is encoded by the PLCB1 gene.
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In membrane biology, fusion is the process by which two initially distinct lipid bilayers merge their hydrophobic cores, resulting in one interconnected structure. If this fusion proceeds completely through both leaflets of both bilayers, an aqueous bridge is formed and the internal contents of the two structures can mix. Alternatively, if only one leaflet from each bilayer is involved in the fusion process, the bilayers are said to be hemifused. In hemifusion, the lipid constituents of the outer leaflet of the two bilayers can mix, but the inner leaflets remain distinct. The aqueous contents enclosed by each bilayer also remain separated.
PIP2 domains are a type of cholesterol-independent lipid domain formed from phosphatidylinositol and positively charged proteins in the plasma membrane. They tend to inhibit GM1 lipid raft function.
Linda Columbus is an American chemist who is Professor of Chemistry and Molecular Physiology at the University of Virginia. Her research considers the structure-function properties of membrane proteins.
Ana Masiulis Jonas was an American biochemist born in Lithuania. She was on the faculty of the University of Illinois Urbana-Champaign (UIUC) from 1974 until 2001. Her research "advanced our understanding of the role lipoproteins play in cardiovascular disease".
References
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- ↑ "Suzanne Scarlata, Chemistry & Biochemistry". WPI. Retrieved 2022-01-08.
- ↑ Rholam, Mohamed; Scarlata, Suzanne; Weber, Gregorio (1984-12-18). "Frictional resistance to the local rotations of fluorophores in proteins". Biochemistry. 23 (26): 6793–6796. doi:10.1021/bi00321a079. ISSN 0006-2960.
- ↑ Scarlata, Suzanne; Rholam, Mohamed; Weber, Gregorio (1984-12-18). "Frictional resistance to local rotations of aromatic fluorophores in some small peptides". Biochemistry. 23 (26): 6789–6792. doi:10.1021/bi00321a078. ISSN 0006-2960.
- ↑ Scarlata, Suzanne Frances; Ropp, Traci; Royer, Catherine A. (1989-08-08). "Histone subunit interactions as investigated by high pressure". Biochemistry. 28 (16): 6637–6641. doi:10.1021/bi00442a016. ISSN 0006-2960. PMID 2790018.
- ↑ Scarlata, S.F. (1991). "Compression of lipid membranes as observed at varying membrane positions". Biophysical Journal. 60 (2): 334–340. Bibcode:1991BpJ....60..334S. doi:10.1016/s0006-3495(91)82058-6. ISSN 0006-3495. PMC 1260069 . PMID 1912276.
- ↑ Runnels, Loren W.; Jenco, John; Morris, Andrew; Scarlata, Suzanne (1996-01-01). "Membrane Binding of Phospholipases C-β1 and C-β2 Is Independent of Phosphatidylinositol 4,5-Bisphosphate and the α and βγ Subunits of G Proteins". Biochemistry. 35 (51): 16824–16832. doi:10.1021/bi961606w. ISSN 0006-2960. PMID 8988021.
- ↑ Rosewitz, Jessica A.; Wang, Shuai; Scarlata, Suzanne F.; Rahbar, Nima (2021-06-01). "An enzymatic self-healing cementitious material". Applied Materials Today. 23: 101035. doi: 10.1016/j.apmt.2021.101035 . ISSN 2352-9407. S2CID 234837645.
- ↑ Guimapang, Katherine (June 21, 2021). "Researchers develop a feasible solution for self-healing concrete in the construction industry". Archinect. Retrieved 2022-01-07.
- ↑ "AAAS Announces Leading Scientists Elected as 2020 Fellows | American Association for the Advancement of Science". www.aaas.org. Retrieved 2022-01-07.
