The Subcellular Distribution of the A and B Proteins of Lactose Synthetase in Bovine and Rat Mammary Tissue

Abstract

Abstract The subcellular distribution of the A and B proteins of lactose synthetase (EC 2.4.1.c) has been determined in bovine and rat mammary tissue. The A protein is mainly associated with the microsomal fraction, whereas the B protein is distributed between the microsomal and soluble fraction. The B protein is more readily dissociated from the microsomes than the A protein. Microsomes present in milk have the same specific activity of the A and B protein as microsomes isolated from mammary tissue.