The Pro-Peptide of the Proβ-Polypeptide Chain of Human β-Hexosaminidase Is Necessary for Proper Protein Folding and Exit from the Endoplasmic Reticulum

Abstract We examine the function of the proβ-peptide (residues 42-121) in the folding and intracellular transport of human β-hexosaminidase B (β-N-acetylhexosaminidase, EC 3.2.1.52). A construct was prepared that encoded an in frame deletion of residues 55-118. Expression of this construct in COS-1 cells produced a β-polypeptide chain that formed insoluble aggregates and remained trapped in the endoplasmic reticulum (ER). We conclude that the proβ-peptide may act as a type of intramolecular chaperone for the mature β-subunit.