Steroidogenic acute regulatory protein
From Wikipedia, the free encyclopedia
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steroidogenic acute regulator
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| Identifiers | |
| Symbol | STAR |
| HUGO | 11359 |
| Entrez | 6770 |
| OMIM | 600617 |
| RefSeq | NM_000349 |
| UniProt | P49675 |
| Other data | |
| Locus | Chr. 8 p11.2 |
The steroidogenic acute regulatory protein, commonly referred to as StAR, is a transport protein that regulates cholesterol transfer within the mitochondria, a rate limiting step in the production of steroid hormones.
Cholesterol needs to be transferred from the outer mitochondrial membrane to the inner membrane where P450scc enzymes is located to split off the cholesterol side chain. 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 been described to facilitate this transfer including: sterol carrier protein 2 (SCP2), steroidogenic activator polypeptide (SAP), peripheral benzodiazepine receptor (PBR), and StAR. However sterol carrier protein 2 and StAR domains are structurally very different.
The gene for StAR is located on chromosome 8p11.2. The protein has 285 amino acids and undergoes truncation when it performs its transport function. StAR is located in the mitochondria of the adrenal and gonadal glands and increases with steroid production, however it has not been found in other tissue that can produce steroids, such as the brain and placenta.[1] These tissues instead produce a homologous protein known as MLN64.
In lipoid congenital adrenal hyperplasia there is a mutation of the gene for StAR resulting in deficient steroidogenesis.
Alcohol suppresses StAR activity.[2]
[edit] References
- ^ Jefcoate C.High-flux mitochondrial cholesterol trafficking, a specialized function of the adrenal cortex. J Clin Invest. 2002 Oct;110(7):881-90. PMID 12370263
- ^ Srivastava VK, Vijayan E, Hiney JK, Dees WL. Effect of ethanol on follicle stimulating hormone-induced steroidogenic acute regulatory protein (StAR) in cultured rat granulosa cells. Alcohol. 2005 Oct;37(2):105-11. PMID 16584974
