ISOLATION OF SINGLE CHAIN PROTEINS WITH FSH SUPPRESSING ACTIVITY FROM FOLLICULAR FLUID

摘要

A series of proteins which suppress follicle stimulating hormone (FSH) secretion in-vitro has been isolated from follicular fluid. The proteins are substantially pure single chain proteins and are characterized by a molecular weight of between 30 kD and 60 kD as estimated by SDS-PAGE in the absence of reducing agents and as having identical NH2- terminal amino acid sequences. The NH2- terminal amino acid sequence comprises G N S/C T/W L R Q A K N G R S/C Q V L Y K wherein S/C and T/W represent alternative amino acids at these positions. The proteins are distinct from inhibin based on NH2- terminal amino acid sequence, molecular mass, absence of subunit structure, absence of inhibin immunoactivity and the failure of inhibin anti-serum to neutralize their bioactivity in-vitro. Their ''inhibin-like'' biological activities based on their ability to suppress FSH cell content of pituitary cells in culture are 5-10% that of bovine 31 kD inhibin.