Partial amino acid sequence of the preprotein form of the alpha subunit of human choriogonadotropin and identification of the site of subsequent proteolytic cleavage
1. Department of Medicine, College of Physicians & Surgeons, Columbia University, New York, N.Y. 10032 USA;1. Department of Obstetrics & Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110 USA
Abstract:
Messenger RNA isolated from first trimester placentae was translated using radiolabeled amino acids in both the wheat germ and the ascites cell-free systems. The choriogonadotropin α subunit product was purified by immunoprecipitation with a subunit specific antiserum. Its amino acid sequence was partially determined by automated Edman degradation analysis. An NH2-terminal extension of 24 amino acids was found and its partial sequence is: