Localization of the pro-sequence within the total deduced primary structure of human beta-hexosaminidase B.
The beta subunit of beta-hexosaminidase (beta-N-acetylhexosaminidase, EC 3.2.1.52) is synthesized in the rough endoplasmic reticulum as a prepropolypeptide. After the loss of the signal peptide and formation of an enzymatically active dimer, the pro-enzyme is either secreted from the cell or transported into the lysosome for processing to its mature form. In order to characterize the early posttranslational events we have purified nearly 1 mg of pro-hexosaminidase B from the NH4Cl containing medium of fibroblasts derived from a patient with the infantile form of Tay-Sachs disease. The partial N-terminal sequence was mapped to a position 42 residues C-terminal to the first in-frame ATG (Met residue) and 79 residues N-terminal to the known mature N-terminus. This position corresponds to that predicted for the cleavage of a 17 amino acid signal peptide generated through the use of the third rather than the first in-frame ATG as the initiation site for protein synthesis.
Stirling
J
J
Department of Biochemistry, Kings College London, England.
Leung
A
A
Gravel
R A
RA
Mahuran
D
D
D000595:Amino Acid Sequence; D004721:Endoplasmic Reticulum / Q000201:enzymology; D004792:Enzyme Precursors / Q000235:genetics*; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D008247:Lysosomes / Q000201:enzymology; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D013661:Tay-Sachs Disease / Q000201:enzymology; D001619:beta-N-Acetylhexosaminidases / Q000235:genetics*
D004792:Enzyme Precursors; D001619:beta-N-Acetylhexosaminidases