FOLLISTATIN AND METHOD OF PURIFYING SAME

摘要

Two follistatin proteins with inhibin-like activity were isolated from porcine follicular fluid using heparin-Sepharose affinity chromatography, followed by gel filtration on Sephacryl S-200 and then six steps of high-performance liquid chromatography. Each isolated molecule is a monomer having a molecular weight of at least about 32,000 daltons. Microsequencing revealed the NH2-terminal portions both to be Gly-Asn-Cys-Trp-Leu- Arg-Gln-Ala-Lys-Asn-Gly-Arg-Cys-Gln-Val-Leu. The larger protein has 315 residues and is believed to be glycosylated. The smaller protein is a 288-residue, C-terminally shortened version thereof. These proteins specifically inhibit basal secretion of FSH, but not of LH, in a rat anterior pituitary monolayer culture system. The half-maximal effective dose for both is 2.5-6.0 ng/ml. Human and rat follistatins exhibit very high homology with the porcine protein, with the human differing from porcine in only 4 residues out of 315 and with the rat differing from porcine in only 8 residues out of 315.