THE PRO-PEPTIDE OF THE PRO-BETA-POLYPEPTIDE CHAIN OF HUMAN BETA-HEXOSAMINIDASE IS NECESSARY FOR PROPER PROTEIN-FOLDING AND EXIT FROM THE ENDOPLASMIC-RETICULUM

We examine the function of the pro beta-peptide (residues 42-121) in t he folding and intracellular transport of human beta-hexosaminidase B (beta-N-acetylhexosaminidase, EC 3.2.1.52). A construct was prepared t hat encoded an in frame deletion of residues 55-118. Expression of thi s construct in COS-1 cells produced a beta-polypeptide chain that form ed insoluble aggregates and remained trapped in the endoplasmic reticu lum (ER). We conclude that the pro beta-peptide may act as a type of i ntramolecular chaperone for the mature beta-subunit. (C) 1994 Academic Press, Inc.