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Identification of glyceraldehyde‐3‐phosphate dehydrogenase as a Ca 2+ ‐dependent fusogen in human neutrophil cytosol
Author(s) -
Hessler Ronald J.,
Blackwood R. Alexander,
Brock Thomas G.,
Francis Joseph W.,
Harsh Donna M.,
Smolen James E.
Publication year - 1998
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.63.3.331
Subject(s) - biology , cytosol , glyceraldehyde 3 phosphate dehydrogenase , dehydrogenase , biochemistry , identification (biology) , glyceraldehyde , neutrophile , enzyme , botany , in vitro
The membrane fusion events observed during neutrophil degranulation are important aspects of the immunoregulatory system. In an attempt to understand the regulation of granule‐plasma membrane fusion, we have begun characterizing human neutrophil cytosol for fusion activity, finding that 50% of the fusogenic activity could be attributed to members of the annexin family of proteins. The major non‐annexin fusion activity (25% of the total cytosolic activity) was enriched by ion exchange chromatography after depletion of annexins by Ca 2+ ‐dependent phospholipid affinity chromatography. The fusion activity co‐purified with a 10,14‐kDa dimer identified as leukocyte L1 (which was non‐fusogenic), along with an approximately 36‐kDa protein. This protein was identified as glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) by amino‐terminal sequencing, and the fusion activity was verified using commercially available GAPDH. GAPDH may play an important role in degranulation because it is as potent as annexin I on a mass basis and may constitute up to 25% of the total cytosolic fusion activity of the neutrophil. J. Leukoc. Biol . 63: 331–336; 1998.