StAR-related Transfer Domain

	StAR-related Transfer Domain START (StAR-related lipid-transfer) is a lipid-binding domain in StAR, HD-ZIP and signalling proteins. The archetypical domain is found in StAR (Steroidogenic acute regulatory protein), a mitochondrial protein that is synthesized in steroid-producing cells. StAR initiates steroid production by mediating the delivery of cholesterol to the first enzyme in steroidogenic pathway. The START domain is critical for this activity, perhaps through the binding of cholesterol. Following the discovery of StAR, 15 START-domain-containing proteins (termed STARD1 through STARD15) were subsequently identified in vertebrates as well as other that are related. Thousands of proteins containing at least one START domain have been determined in invertebrates, bacteria and plants to form a larger superfamily, variously known as START, Bet v1-like or SRPBCC (START/RHOalphaC/ PITP/Bet v1/CoxG/CalC) domain proteins, all of which bind hydrophobic ligands. In the case of plants, many of the START pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Steroidogenic Acute Regulatory Protein The steroidogenic acute regulatory protein, commonly referred to as StAR (STARD1), is a transport protein that regulates cholesterol transfer within the mitochondria, which is the rate-limiting step in the production of steroid hormones. It is primarily present in steroid-producing cells, including theca cells and luteal cells in the ovary, Leydig cells in the testis and cell types in the adrenal cortex. Function Cholesterol needs to be transferred from the outer mitochondrial membrane to the inner membrane where cytochrome P450scc enzyme (CYP11A1) cleaves the cholesterol side chain, which is the first enzymatic step in all steroid synthesis. The aqueous phase between these two membranes cannot be crossed by the lipophilic cholesterol, unless certain proteins assist in this process. A number of proteins have historically been proposed to facilitate this transfer including: sterol carrier protein 2 (SCP2), steroidogenic activator polypeptide (SAP), peripheral benzodia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Cyclase A cyclase is an enzyme, almost always a lyase, that catalyzes a chemical reaction to form a cyclic compound. Important cyclase enzymes include: * Adenylyl cyclase, which forms cyclic AMP from adenosine triphosphate (EC 4.6.1.1) ADCY1 ADCY2 ADCY3 ADCY4 ADCY5 ADCY6 ADCY7 ADCY8 ADCY9 ADCY10 * Guanylyl cyclase, which forms cyclic GMP from guanosine triphosphate Guanosine-5'-triphosphate (GTP) is a purine nucleoside triphosphate. It is one of the building blocks needed for the synthesis of RNA during the transcription process. Its structure is similar to that of the guanosine nucleoside, the only ... (EC 4.6.1.2) GUCY1A2 GUCY1A3 GUCY1B3 Guanylate cyclase 2C Guanylate cyclase 2D Guanylate cyclase 2F NPR1 NPR2 * Protein cyclase, a ligase enzyme that produces backbone-cyclised proteins by intramolecular transpeptidation {{enzyme index EC 4.6.1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	ACOT11 Acyl-coenzyme A thioesterase 11 also known as StAR-related lipid transfer protein 14 (STARD14) is an enzyme that in humans is encoded by the ''ACOT11'' gene. This gene encodes a protein with acyl-CoA thioesterase activity towards medium (C12) and long-chain (C18) fatty acyl-CoA substrates which relies on its StAR-related lipid transfer domain. Expression of a similar murine protein in brown adipose tissue is induced by cold exposure and repressed by warmth. Expression of the mouse protein has been associated with obesity, with higher expression found in obesity-resistant mice compared with obesity-prone mice. Alternative splicing results in two transcript variants encoding different isoforms. Structure The ACOT11 gene is located on the 1st chromosome, with its specific localization being 1p32.3. It contains 18 exons. The protein encoded by this gene contains 258 amino acids, and forms a homodimer with another chain. Its theoretical weight is 26.67 kDa. The protein contains a St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	STARD13 StAR-related lipid transfer domain protein 13 (STARD13) also known as deleted in liver cancer 2 protein (DLC-2) is a protein that in humans is encoded by the ''STARD13'' gene and a member of the DLC family of proteins. Function and structure STARD13 serves as a Rho GTPase-activating protein (GAP), a type of protein that regulates members of the Rho family of GTPases. It selectively activates RhoA and CDC42 and suppresses cell growth by inhibiting actin stress fiber assembly. The protein consists of an N-terminal sterile alpha motif (SAM) domain, a serine-rich domain, a RhoGAP domain and at the C-terminus, a StAR-related lipid-transfer domain ( START). Tissue distribution and pathology The protein was identified in part through its differential expression in cancers Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	DLC1 Deleted in Liver Cancer 1 also known as DLC1 and StAR-related lipid transfer protein 12 (STARD12) is a protein which in humans is encoded by the ''DLC1'' gene. This gene is deleted in the primary tumor of hepatocellular carcinoma. It maps to 8p22-p21.3, a region frequently deleted in solid tumors. It is suggested that this gene is a candidate tumor suppressor gene for human liver cancer, as well as for prostate, lung, colorectal, and breast cancers. Gene The human ''DLC1'' gene is located on the short arm of chromosome 8 (8p21.3-22), within a region that frequently undergoes loss of heterozygosity by either genomic deletion or epigenetic silencing mechanisms in several types of solid cancers. The gene contains 14 exons and produces an mRNA transcript that is 6.3 kb in length; the second AUG present in the open reading frame is the major translational start site, and produces a polypeptide which is 1091 amino acids long. The promoter region of the ''DLC1'' gene contains a CpG ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	STARD8 StAR-related lipid transfer domain protein 8 (STARD8) also known as deleted in liver cancer 3 protein (DLC-3) is a protein that in humans is encoded by the ''STARD8'' gene and is a member of the DLC family. Structure and function The protein is 1103 amino acids long, which like other DLC proteins consists of a sterile alpha motif (SAM), RhoGAP and a StAR-related lipid-transfer (START) domains. The protein is a Rho GTPase-activating protein (GAP), a type of protein that regulates members of the Rho family of GTPases. STARD8 is characterized as activating Rho GTPases. Its expression inhibits the growth of human breast and prostate cancer cells in culture. Tissue distribution and pathology The protein is expressed in tissues throughout the body, but is absent or reduced in many kinds of tumor cells. While there are no known disorders caused by STARD8, partial loss of the ''STARD8'' gene occurs in cases of craniofrontonasal syndrome where the EFNB1 Ephrin B1 is a protein tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	COL4A3BP Collagen type IV alpha-3-binding protein, also known as ceramide transfer protein (CERT) or StAR-related lipid transfer protein 11 (STARD11) is a protein that in humans is encoded by the ''COL4A3BP'' gene. The protein contains a pleckstrin homology domain at its amino terminus and a START domain towards the end of the molecule. It is a member of the StarD2 subfamily of START domain proteins. Function and structure Ceramide transferase protein (or CERT) is responsible for the transfer of ceramide from the endoplasmic reticulum (ER) to the Golgi apparatus. Ceramide plays a very important role in the metabolism and biosynthesis of sphingolipid. More specifically, it is synthesized at the ER, then is transferred by CERT to Golgi where it is converted to sphingomyelin (SM). There are two pathways through which this transfer takes place: a major pathway, which is ATP and cytosol-dependent and a minor pathway, which is ATP- and cytosol-independent. CERT is a 68kDa protein that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	STARD10 StAR-related lipid transfer protein 10 (STARD10) or PCTP-like protein is a lipid transfer protein that in humans is encoded by the ''STARD10'' gene. The protein derives its name from the fact that the molecule contains a START domain. As part of the StarD2 subfamily, StarD10 can transport the lipids phosphatidylcholine and phosphatidylethanolamine between membranes in solution. Casein kinase II phosphorylates In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, whi ... the protein on its serine at position 184. The function of StarD10 in the cell is not yet understood. Its expression is associated with cancer, but the nature of its role is unclear. Most recent data indicate that loss of StarD10 expression in breast cancer is associated with poor outcomes in patients. References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	STARD7 StAR-related lipid transfer domain protein 7 (STARD7) or gestational trophoblastic tumor gene-1 (GTT1) is a lipid transporter that specifically binds and transports phosphatidylcholine between membranes. Function and tissue distribution StarD7 is found in the cytosol and associated with the mitochondrion. When overproduced in the cell, mitochondrial levels of phosphatidylcholine rise. High levels of the protein are found in tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ... cells compared to normal cells, suggesting a role in cell proliferation. Structure There are two forms of StarD7: StarD7-I and StarD7-II. The former is 295 amino acids long. StarD7-I possesses an additional 75 amino acids at its amino-terminus, which form a signaling sequence that targets it to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Phosphatidylcholine Transfer Protein Phosphatidylcholine transfer protein (PCTP) also known as StAR-related lipid transfer domain protein 2 (STARD2) is a specific intracellular phospholipid binding protein that can transfer phosphatidylcholine between different membranes in the cytosol. In humans, phosphatidylcholine transfer protein is encoded by the ''PCTP'' gene. Function PCTP transfers phosphatidylcholine molecules between membranes ''in vitro''. Further studies found that sensitivity to phosphatidylcholine levels causes PCTP to interact with select enzymes, promoting their activation. PCTP stimulates the acyl-CoA thioesterase activity of thioesterase superfamily member 2 (Them2)/acyl-CoA thioesterase 13 (ACOT13) and the activity of homeodomain transcription factor paired box gene 3 (PAX3). Protein kinase C phosphorylation promotes localization of PCTP to the mitochondrion where it may activate Them2. Structure This soluble protein is 214 amino acids long. It is almost entirely composed of a StAR-related tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	STARD5 StAR-related lipid transfer protein 5 is a protein that in humans is encoded by the ''STARD5'' gene. The protein is a 213 amino acids long, consisting almost entirely of a StAR-related transfer (START) domain. It is also part of the StarD4 subfamily of START domain proteins, sharing 34% sequence identity with STARD4. Function The protein is most prevalent in the kidney and the liver where it is found in Kupffer cells. STARD5 binds both cholesterol and 25-hydroxycholesterol and appears to function to redistribute cholesterol to the endoplasmic reticulum with which the protein associates and/or the plasma membrane. Increased levels of StarD5 increase free cholesterol in the cell. Cholesterol homeostasis is regulated, at least in part, by sterol regulatory element (SRE)-binding proteins (e.g., SREBP1) and by liver X receptor The liver X receptor (LXR) is a member of the nuclear receptor family of transcription factors and is closely related to nuclear receptors such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	STARD4 StAR-related lipid transfer protein 4 (STARD4) is a soluble protein involved in cholesterol transport. It can transfer up to 7 sterol molecules per minute between artificial membranes. Function STARD4 may regulate cholesterol levels in many cells, including in the liver. STARD4 has specifically been linked to the movement of cholesterol to the endoplasmic reticulum. The protein is associated with the endoplasmic reticulum and lipid droplets. Increases in the protein relate to cell stress. High levels of STARD4 increases the synthesis of bile acids and cholesterol esters in liver hepatocytes. Reductions in cholesterol synthesis by cells increase STARD4 levels while StarD4 declines in mice fed a high cholesterol diet. Increases in levels of either master gene regulator SREBP-1a or SREBP2, which both promote the production of proteins involved in cholesterol synthesis, increase StarD4 levels in mouse liver. Conversely, increased STARD4 increases active SREBP2 levels. Los ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]