Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.
Vitam Horm. 2011;85:149-84. doi: 10.1016/B978-0-12-385961-7.00008-1.
Inhibin A and B, dimeric glycoproteins comprising an α- and β((A/B))-subunit, negatively regulate follicle stimulating hormone (FSH) synthesis by the pituitary. The expression of α- and β-subunits within Sertoli cells of the testis and granulosa cells of the ovary is controlled by a range of transcription factors, including CREB, SP-1, Smads, and GATA factors. The inhibin α- and β-subunits are synthesized as precursor molecules consisting of an N-terminal propeptide and a C-terminal mature domain. Recently, we showed that hydrophobic residues within the propeptides of the α- and β-subunits interact noncovalently with their mature domains, maintaining the molecules in a conformation competent for dimerization. Dimeric precursors are cleaved by proprotein convertases and mature inhibins are secreted from the cell noncovalently associated with their propeptides. Propeptides may increase the half-life of inhibin A and B in circulation, but they are readily displaced in the presence of the high-affinity receptors, betaglycan, and ActRII.
抑制素 A 和 B 是二聚糖蛋白，由 α-和 β((A/B))-亚基组成，通过垂体负调控卵泡刺激素 (FSH) 的合成。睾丸支持细胞和卵巢颗粒细胞中 α-和 β-亚基的表达受一系列转录因子的调控，包括 CREB、SP-1、Smads 和 GATA 因子。抑制素 α-和 β-亚基作为前体分子合成，由 N 端前肽和 C 端成熟结构域组成。最近，我们发现 α-和 β-亚基前肽中的疏水性残基与它们的成熟结构域非共价相互作用，使分子处于适合二聚化的构象。前体蛋白被蛋白水解酶切割，成熟的抑制素与前肽非共价结合后从细胞中分泌出来。前肽可能会增加抑制素 A 和 B 在循环中的半衰期，但在高亲和力受体β-聚糖和 ActRII 存在的情况下，它们很容易被取代。
