Parotin subunit as a potent polyclonal B cell activator binds to newly found glycosylphosphatidylinositol (GPI)-anchored proteins on human B cell surfaces.
Parotin subunit (PS) is a unique glycoprotein, isolated from bovine parotid glands, which possesses the ability to induce polyclonal antibody production and IL-1-like activity. The present studies investigated the existence of receptors for PS on B cell surfaces using PS-affinity chromatography. No PS-binding proteins (PSR) solubilized from human B cell surfaces with Triton X-100 were detected, whereas the PSR released from human B cell membranes with phosphatidylinositol-specific phospholipase C (PI-PLC) treatment were composed of 75- and 40-kDa proteins. PI-PLC treatment markedly reduced polyclonal antibody responses to PS but weakly inhibited the responses to PWM, xanthan gum, and LPS in human and mouse lymphocytes. Addition of PSR caused a dose-related reduction in polyclonal IgM and IgG antibody responses to PS. These results suggest that PSR can act as glycosylphosphatidylinositol-anchored receptors for PS.
Ishizaka
S
S
Third Department of Internal Medicine, Nara Medical University, Japan.
Kimoto
M
M
Tsujii
T
T
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002352:Carrier Proteins / Q000032:analysis* / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D012471:Salivary Proteins and Peptides / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction
D002352:Carrier Proteins; D017261:Glycosylphosphatidylinositols; D012471:Salivary Proteins and Peptides