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Localization of the pro‐sequence within the total deduced primary structure of human β‐hexosaminidase B
Author(s) -
Stirling John,
Leung Amy,
Gravel Roy A.,
Mahuran Don
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80699-9
Subject(s) - endoplasmic reticulum , signal peptide , cleavage (geology) , hexosaminidase , n terminus , peptide sequence , peptide , lysosome , biochemistry , residue (chemistry) , protein primary structure , protein subunit , chemistry , dimer , enzyme , microbiology and biotechnology , stereochemistry , biology , gene , paleontology , organic chemistry , fracture (geology)
The β subunit of β‐hexosaminidase (β‐ 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 NH 4 Cl 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.