A novel "Cleaved Prolactin" in the rat pituitary: Part I biosynthesis, characterization and regulatory control

Abstract

A new form of prolactin which has a cleavage in its large disulphide loop and is synthesised and secreted by rat pituitary glands radioactively labelled in vitro has been detected on sodium dodecyl sulphate polyacrylamide gel analysis and identified by tryptic fingerprinting; this form of prolactin was also found in fresh pituitary glands. The molecule is a 2-chain structure; the 2 component polypeptide chains are separable into an N-terminal 16,000 dalton and a C-terminal 8,000 dalton fragment by the reduction of the intervening disulphide bridge. The cleaved prolactin is a post-translationally modified form of the hormone whose production is regulated by physiological and pharmacological stimuli.