title: Purification and characterization of the 22,000-dalton GTP-binding protein substrate for ADP-ribosylation by botulinum toxin, G22K.
abstract: GTP-binding proteins were purified from human neutrophils, including a 40,000-Da pertussis toxin substrate (Gn) and 22,000-, 24,000-, and 26,000-Da proteins, termed G22K, G24K, and G26K, respectively. The latter proteins were shown to be immunologically unrelated to Gn. G22K cross-reacted with anti-ras monoclonal antibody 142-24EO5, but not with monoclonal antibody Y13-259. A single 22,000-Da substrate for botulinum toxin-catalyzed ADP-ribosylation present in neutrophil membranes co-migrated upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis with G22K. In the presence of a cytosolic factor, G22K could serve as a specific botulinum toxin substrate. The 22,000-Da botulinum toxin substrate in neutrophil membranes could be immunoprecipitated by antibody 142-24EO5, but not by antibody Y13-259. G22K appears to be a unique GTP-binding protein which serves as a substrate for ADP-ribosylation by a component of botulinum toxin and which may be involved in exocytotic secretion or cellular differentiation.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000595:Amino Acid Sequence; D001905:Botulinum Toxins / Q000378:metabolism*; D002454:Cell Differentiation; D003429:Cross Reactions; D005089:Exocytosis; D019204:GTP-Binding Proteins / Q000302:isolation & purification*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D037342:Pertussis Toxin; D011518:Proto-Oncogene Proteins / Q000032:analysis; D016283:Proto-Oncogene Proteins p21(ras); D010566:Virulence Factors, Bordetella / Q000378:metabolism
chemical_list: D011518:Proto-Oncogene Proteins; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D037342:Pertussis Toxin; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)