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Evidence that fructose 1,6‐bisphosphate specifically protects the α‐subunit of pyrophosphate‐dependent 6‐phosphofructo‐1‐phosphotransferase against proteolytic degradation
Author(s) -
Wang Yue-Hao,
Shi Jiao-Nai
Publication year - 1999
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/s0014-5793(99)01304-6
Subject(s) - protein subunit , proteolysis , pyrophosphate , biochemistry , chemistry , g alpha subunit , phosphotransferase , microbiology and biotechnology , biology , enzyme , gene
Pyrophosphate‐dependent 6‐phosphofructo‐1‐phosphotransferase (PFP) consists of α (regulatory) and β (catalytic) subunits. The α‐subunit was previously reported to be much more susceptible to tryptic digestion than the β‐subunit. In this study, ligand‐induced protection of PFP subunits against proteolysis by subtilisin was investigated in vitro and the data obtained demonstrated that fructose 1,6‐bisphosphate (Fru‐1,6‐P 2 ), while exerting negligible effect on the β‐subunit, remarkably protected the α‐subunit against proteolytic degradation. Western blot analysis revealed a good correlation between the Fru‐1,6‐P 2 concentration and the degree of corresponding protection on the α‐subunit against proteolysis. In contrast, none of other examined ligands including fructose 2,6‐bisphosphate, fructose 6‐phosphate and pyrophosphate had such protection on the α‐subunit. This finding (1) indicates that the stability of the α‐subunit can be selectively increased by Fru‐1,6‐P 2 , and (2) suggests that Fru‐1,6‐P 2 is likely a special effector of the α‐subunit.