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Steroidogenic Acute Regulatory Protein

Meaning

The Steroidogenic Acute Regulatory Protein, universally known as StAR, is a crucial mitochondrial protein that serves as the rate-limiting step in the synthesis of all steroid hormones, including cortisol, aldosterone, testosterone, and estrogen. Its function is to facilitate the rapid transfer of cholesterol, the precursor molecule, from the outer to the inner mitochondrial membrane, where the initial enzymatic conversion takes place. The presence and activity of StAR are directly correlated with the acute hormonal output of steroidogenic tissues like the adrenals and gonads.