Phosphotyrosine-dependent association between CD22 and protein tyrosine phosphatase 1C.
CD22 is a B lymphocyte-specific cell surface glycoprotein that becomes tyrosine phosphorylated upon B cell activation. To determine if tyrosine phosphorylated CD22 couples signaling through membrane immunoglobulin (mIg) to down-stream elements, we looked for molecules coprecipitating with CD22 after anti-Ig stimulation. We found that a 60-kDa molecule was stably associated with CD22 following cross-linking of mIg and have identified this molecule as protein tyrosine phosphatase 1C (PTP1C). The association between PTP1C and CD22 is dependent upon tyrosine phosphorylation of CD22, but does not appear to require tyrosine phosphorylation of PTP1C.
Campbell
M A
MA
Department of Immunology, Scripps Research Institute, La Jolla, CA 92037, USA.
Klinman
N R
NR
D000818:Animals; D000906:Antibodies / Q000378:metabolism; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D015815:Cell Adhesion Molecules; D007136:Immunoglobulins / Q000276:immunology / Q000378:metabolism; D037102:Lectins; D051379:Mice; D008807:Mice, Inbred BALB C; D019000:Phosphotyrosine; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011940:Receptor Aggregation; D051918:Sialic Acid Binding Ig-like Lectin 2; D015398:Signal Transduction; D013154:Spleen / Q000276:immunology; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D000906:Antibodies; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C497868:Cd22 protein, mouse; D015815:Cell Adhesion Molecules; D007136:Immunoglobulins; D037102:Lectins; D051918:Sialic Acid Binding Ig-like Lectin 2; D019000:Phosphotyrosine; D014443:Tyrosine; D017027:Protein Tyrosine Phosphatases