Association with B-cell-antigen receptor with protein-tyrosine kinase p72syk and activation by engagement of membrane IgM.
We have demonstrated that a 72-kDa non-receptor-type protein-tyrosine kinase (p72syk) was co-immunoprecipitated with membrane IgM in digitonin lysates of porcine tonsillar cells and was rapidly activated following the engagement of membrane IgM. This activation was occurred within 5 s, even in the presence of EGTA and 5,5'-dimethyl-bis-(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid as extracellular and intracellular Ca(2+)-chelating agents, respectively, as well as in the presence of the protein-kinase-C inhibitor, H-7. Additionally, genistein, a potent protein-tyrosine kinase inhibitor, was capable of reducing both IgM-stimulated Ca2+ mobilization and p72syk activation in a dose-dependent manner. These results indicate that p72syk is physically associated with the B-cell-antigen receptor, participating in antigen-mediated signal transduction in both a Ca(2+)-independent and protein-kinase-C-independent manners.
Yamada
T
T
Department of Biochemistry, Fukui Medical School, Matsuoka, Japan.
Taniguchi
T
T
Yang
C
C
Yasue
S
S
Saito
H
H
Yamamura
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019833:Genistein; D007075:Immunoglobulin M / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D007529:Isoflavones / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D013552:Swine; D000072377:Syk Kinase
D004792:Enzyme Precursors; D007075:Immunoglobulin M; D047908:Intracellular Signaling Peptides and Proteins; D007529:Isoflavones; D011947:Receptors, Antigen, B-Cell; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; D011493:Protein Kinase C; D002118:Calcium