| START | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 star-related lipid transport domain of mln64 | |||||||||
| Identifiers | |||||||||
| Symbol | START | ||||||||
| Pfam | PF01852 | ||||||||
| Pfam clan | CL0209 | ||||||||
| InterPro | IPR002913 | ||||||||
| SMART | START | ||||||||
| SCOP2 | 1em2 / SCOPe / SUPFAM | ||||||||
| OPM superfamily | 138 | ||||||||
| OPM protein | 1ln1 | ||||||||
| Membranome | 564 | ||||||||
| |||||||||
| START domain | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | START | ||||||||
| Pfam | PF01852 | ||||||||
| InterPro | IPR002913 | ||||||||
| SMART | START | ||||||||
| SCOP2 | 1em2 / SCOPe / SUPFAM | ||||||||
| TCDB | 9.B.64 | ||||||||
| CDD | cd00177 | ||||||||
| |||||||||
START (StAR-related lipid-transfer) is a lipid-binding domain in StAR, HD-ZIP and signalling proteins.[1] The archetypical domain is found in StAR (Steroidogenic acute regulatory protein), a mitochondrial protein that is synthesized in steroid-producing cells.[2] StAR initiates steroid production by mediating the delivery of cholesterol to the first enzyme in the 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 proteins fall into the category of putative lipid/sterol-binding homeodomain (HD) transcription factors or HD-START proteins.[3]
Representatives of the START domain family bind different substances or ligands such as sterols (e.g., StAR or STARD1) and lipids like phosphatidylcholine (phosphatidylcholine transfer protein, also called PCTP or STARD2) and have enzymatic activities. Ligand binding by the START domain in multidomain proteins can also regulate the activities of the other domains, such as the RhoGAP domain, the homeodomain and the thioesterase domain.[1][4]
- ^ a b Ponting CP, Aravind L (1999). "START: a lipid-binding domain in StAR, HD-ZIP and signalling proteins". Trends Biochem. Sci. 24 (4): 130–132. doi:10.1016/S0968-0004(99)01362-6. PMID 10322415.
- ^ Clark BJ, Wells J, King SR, Stocco DM (1994). "The purification, cloning, and expression of a novel luteinizing hormone-induced mitochondrial protein in MA-10 mouse Leydig tumor cells. Characterization of the steroidogenic acute regulatory protein (StAR)". J. Biol. Chem. 269 (45): 28314–28322. doi:10.1016/S0021-9258(18)46930-X. PMID 7961770.
- ^ Schrick K, Nguyen D, Karlowski WM, Mayer KF (2004). "START lipid/sterol-binding domains are amplified in plants and are predominantly associated with homeodomain transcription factors". Genome Biol. 5 (6): R41. doi:10.1186/gb-2004-5-6-r41. PMC 463074. PMID 15186492.
- ^ Koonin EV, Aravind L, Iyer LM (2001). "Adaptations of the helix-grip fold for ligand binding and catalysis in the START domain superfamily". Proteins. 43 (2): 134–144. doi:10.1002/1097-0134(20010501)43:2<134::AID-PROT1025>3.0.CO;2-I. PMID 11276083. S2CID 6322401.