P49675

StAR plays a crucial role in steroid hormone synthesis by facilitating cholesterol transport into mitochondria, where conversion to pregnenolone occurs as the precursor for all steroid hormones. This transport represents the first and rate-limiting step in steroidogenesis, making StAR essential for producing hormones such as cortisol, aldosterone, and sex steroids. StAR expression is particularly important in gonads and adrenal glands, where tropic hormones modulate production, and mutations can lead to severe endocrine disorders, including lipoid congenital adrenal hyperplasia. StAR protein shows predominant expression in ovary and testis, with immunoreactivity shifting from granulosa cells in early antral follicles to theca cell layers in mature follicles, highlighting a dynamic role in reproductive physiology.