Butyrophilin | |
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Identifiers | |
Symbol | Butyrophilin |
Membranome | 14 |
Butyrophilin, subfamily 1, member A1 | |||||||
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Identifiers | |||||||
Symbol | BTN1A1 | ||||||
NCBI gene | 696 | ||||||
HGNC | 1135 | ||||||
RefSeq | NP_001723 | ||||||
UniProt | Q13410 | ||||||
Other data | |||||||
Locus | Chr. 6 p22.2 | ||||||
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Butyrophilin, subfamily 2, member A2 | |||||||
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Identifiers | |||||||
Symbol | BTN2A2 | ||||||
NCBI gene | 10385 | ||||||
HGNC | 1137 | ||||||
RefSeq | NP_008926 | ||||||
UniProt | Q8WVV5 | ||||||
Other data | |||||||
Locus | Chr. 6 p22.2 | ||||||
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Butyrophilin, subfamily 3, member A1 | |||||||
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Identifiers | |||||||
Symbol | BTN3A1 | ||||||
NCBI gene | 11119 | ||||||
HGNC | 1138 | ||||||
RefSeq | NP_008979 | ||||||
UniProt | O00481 | ||||||
Other data | |||||||
Locus | Chr. 6 p22.2 | ||||||
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Butyrophilins are membrane proteins belonging to the immunoglobulin superfamily (Ig). [1] [2] Butyrophilin (Btn) genes constitute a subgroup of at least 10 genes in the Ig superfamily identified in human, mouse, cow, goat and other species. [3]
The eponymous Btn gene (BTN1A1 in humans; Btn1a1 in mouse) is highly expressed in the secretory epithelium of the mammary gland during lactation. Other homologues are predominantly expressed in skeletal muscle and the intestine and erythroid cells. In contrast, BTN2A1 and 2 and BTN3A1, 2, and 3 are widely expressed in many tissues, suggesting that the structural domains of Btn proteins may have both universal and tissue-specific functions.
Types include:
Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pituitary gland in response to eating, mating, estrogen treatment, ovulation and nursing. It is secreted heavily in pulses in between these events. Prolactin plays an essential role in metabolism, regulation of the immune system and pancreatic development.
Lipolysis is the metabolic pathway through which lipid triglycerides are hydrolyzed into a glycerol and free fatty acids. It is used to mobilize stored energy during fasting or exercise, and usually occurs in fat adipocytes. The most important regulatory hormone in lipolysis is insulin; lipolysis can only occur when insulin action falls to low levels, as occurs during fasting. Other hormones that affect lipolysis include glucagon, epinephrine, norepinephrine, growth hormone, atrial natriuretic peptide, brain natriuretic peptide, and cortisol.
A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word mamma, "breast". The mammary glands are arranged in organs such as the breasts in primates, the udder in ruminants, and the dugs of other animals. Lactorrhea, the occasional production of milk by the glands, can occur in any mammal, but in most mammals, lactation, the production of enough milk for nursing, occurs only in phenotypic females who have gestated in recent months or years. It is directed by hormonal guidance from sex steroids. In a few mammalian species, male lactation can occur. With humans, male lactation can occur only under specific circumstances.
Mouse mammary tumor virus (MMTV) is a milk-transmitted retrovirus like the HTL viruses, HI viruses, and BLV. It belongs to the genus Betaretrovirus. MMTV was formerly known as Bittner virus, and previously the "milk factor", referring to the extra-chromosomal vertical transmission of murine breast cancer by adoptive nursing, demonstrated in 1936, by John Joseph Bittner while working at the Jackson Laboratory in Bar Harbor, Maine. Bittner established the theory that a cancerous agent, or "milk factor", could be transmitted by cancerous mothers to young mice from a virus in their mother's milk. The majority of mammary tumors in mice are caused by mouse mammary tumor virus.
Glucose transporter type 4 (GLUT4), also known as solute carrier family 2, facilitated glucose transporter member 4, is a protein encoded, in humans, by the SLC2A4 gene. GLUT4 is the insulin-regulated glucose transporter found primarily in adipose tissues and striated muscle. The first evidence for this distinct glucose transport protein was provided by David James in 1988. The gene that encodes GLUT4 was cloned and mapped in 1989.
The prolactin receptor (PRLR) is a type I cytokine receptor encoded in humans by the PRLR gene on chromosome 5p13-14. It is the receptor for prolactin (PRL). The PRLR can also bind to and be activated by growth hormone (GH) and human placental lactogen (hPL). The PRLR is expressed in the mammary glands, pituitary gland, and other tissues. It plays an important role in lobuloalveolar development of the mammary glands during pregnancy and in lactation.
Chemokine ligand 28 (CCL28), also known as mucosae-associated epithelial chemokine (MEC), CCK1 and SCYA28, is a chemokine. CCL28 regulates the chemotaxis of cells that express the chemokine receptors CCR3 and CCR10. CCL28 is expressed by columnar epithelial cells in the gut, lung, breast and the salivary glands and drives the mucosal homing of T and B lymphocytes that express CCR10, and the migration of eosinophils expressing CCR3. This chemokine is constitutively expressed in the colon, but its levels can be increased by pro-inflammatory cytokines and certain bacterial products implying a role in effector cell recruitment to sites of epithelial injury. CCL28 has also been implicated in the migration of IgA-expressing cells to the mammary gland, salivary gland, intestine and other mucosal tissues. It has also been shown as a potential antimicrobial agent effective against certain pathogens, such as Gram negative and Gram positive bacteria and the fungus Candida albicans.
Hormone-sensitive lipase (EC 3.1.1.79, HSL), also previously known as cholesteryl ester hydrolase (CEH), sometimes referred to as triacylglycerol lipase, is an enzyme that, in humans, is encoded by the LIPE gene, and catalyzes the following reaction:
Bile salt-dependent lipase, also known as carboxyl ester lipase is an enzyme produced by the adult pancreas and aids in the digestion of fats. Bile salt-stimulated lipase is an equivalent enzyme found within breast milk. BSDL has been found in the pancreatic secretions of all species in which it has been looked for. BSSL, originally discovered in the milk of humans and various other primates, has since been found in the milk of many animals including dogs, cats, rats, and rabbits.
Mannose-6-phosphate receptor binding protein 1 (M6PRBP1) is a protein which in humans is encoded by the M6PRBP1 gene. Its gene product, as well as the gene itself, is commonly known as TIP47.
Milk fat globule-EGF factor 8 protein (Mfge8), also known as lactadherin, is a protein that in humans is encoded by the MFGE8 gene.
Butyrophilin subfamily 1 member A1 is a protein that in humans is encoded by the BTN1A1 gene.
Butyrophilin subfamily 2 member A2 is a protein that in humans is encoded by the BTN2A2 gene.
Cell death activator CIDE-A is a protein that in humans is encoded by the CIDEA gene. Cidea is an essential transcriptional coactivator regulating mammary gland secretion of milk lipids.
Fat globules are individual pieces of intracellular fat in human cell biology. The lipid droplet's function is to store energy for the organism's body and is found in every type of adipocytes. They can consist of a vacuole, droplet of triglyceride, or any other blood lipid, as opposed to fat cells in between other cells in an organ. They contain a hydrophobic core and are encased in a phospholipid monolayer membrane. Due to their hydrophobic nature, lipids and lipid digestive derivatives must be transported in the globular form within the cell, blood, and tissue spaces.
Uterine serpins are members of the A clade of the serine protease inhibitor (serpin) superfamily of proteins and are encoded by the SERPINA14 gene. Uterine serpins are produced by the endometrium of a restricted group of mammals under the influence of progesterone or estrogen. These proteins appear to be inactive protease inhibitors and may function during pregnancy to regulate immune function or participate in transplacental transport.
Fat storage-inducing transmembrane protein 2 is a protein that in humans is encoded by the FITM2 gene. It plays a role in fat storage. Its location is 20q13.12 and it contains 2 exons. It is also a member of the FIT protein family that has been conserved throughout evolution. Conserved from Saccharomyces cerevisiae to humans is the capability to take fat and store it as cytoplasmic triglyceride droplets. While FIT proteins facilitate the segregation of triglycerides (TGs) into cytosolic lipid droplets, they are not involved in triglyceride biosynthesis. In mammals, both FIT2 and FIT1 from the same family are present, embedded in the wall of the endoplasmic reticulum (ER) where they regulate lipid droplet formation in the cytosol. In S. cerevisiae, it also plays a role in the metabolism of phospholipids. These TGs are in the cytoplasm, encapsulated by a phospholipid monolayer in configurations or organelles that have been given many different names including lipid particles, oil bodies, adiposomes, eicosasomes, and most prevalent in scientific research – lipid droplets.
Milk fat globule membrane (MFGM) is a complex and unique structure composed primarily of lipids and proteins that surrounds milk fat globule secreted from the milk producing cells of humans and other mammals. It is a source of multiple bioactive compounds, including phospholipids, glycolipids, glycoproteins, and carbohydrates that have important functional roles within the brain and gut.
Perilipin 5, also known as Oxpatperilipin 5 or PLIN5, is a protein that belongs to perilipin family. This protein group has been shown to be responsible for lipid droplet's biogenesis, structure and degradation. In particular, Perilipin 5 is a lipid droplet-associated protein whose function is to keep the balance between lipolysis and lipogenesis, as well as maintaining lipid droplet homeostasis. For example, in oxidative tissues, muscular tissues and cardiac tissues, PLIN5 promotes association between lipid droplets and mitochondria.
Melanocortin 2 receptor accessory protein is a transmembrane accessory protein that in humans is encoded by the MRAP gene located in chromosome 21q22.11. Alternate splicing of the MRAP mRNA generates two functionally isoforms MRAP-α and MRAP-β.