STAR (gene)

STAR (Steroidogenic Acute Regulatory Protein) is a protein that in humans is encoded by the STAR gene. It is a key regulator of steroid hormone synthesis in both the adrenal gland and the gonads.

Function

The STAR protein facilitates the transport of cholesterol from the outer mitochondrial membrane to the inner mitochondrial membrane, where it is converted to pregnenolone, the first step in the synthesis of steroid hormones. This process is also known as steroidogenesis.

Clinical significance

Mutations in the STAR gene can lead to Congenital Lipoid Adrenal Hyperplasia, a rare, potentially fatal disease characterized by an inability to synthesize steroid hormones. Symptoms can include salt-wasting, hypoglycemia, and ambiguous genitalia in affected infants.

Structure

The STAR protein is composed of 285 amino acids and has a molecular weight of approximately 30 kDa. It contains a lipid-binding domain and a mitochondrial targeting sequence.

See also

• Steroidogenesis
• Congenital Lipoid Adrenal Hyperplasia
• Mitochondrial membrane transport

External links

• STAR at NCBI Gene
• STAR at Genetics Home Reference