Four CD45/P56lck-associated phosphorproteins (pp29-pp32) undergo alterations in human T cell activation.
In human T lymphocytes a functional complex is formed between the protein tyrosine phosphatase CD45, the protein tyrosine kinase p56lck and a phosphoprotein, pp32, a possible common substrate. Here we demonstrate that the previously described pp32 protein is composed of two distinct molecules (pp29 and pp32) in both resting human T lymphocytes and continuously proliferating T lymphoma lines. Importantly, T lymphocyte activation employing CD2 monoclonal antibodies (mAb), CD3 mAb or phorbol 12, 13 dibutyrate results in loss of pp29 and pp32 from the CD45/p56lck molecular complex and concomitant association of two distinct phosphoproteins with different molecular weights (pp30 and pp31). These events appear to be unrelated to clonal T cell growth but rather depend on receptor-mediated differentiation signals. Reprecipitation experiments employing an antiserum directed at a consensus sequence of GTP-binding proteins suggest that all four pp29-pp32 molecules might represent proteins with GTP-binding properties. Biochemical analysis of pp29-pp32 employing V8-protease digestion indicates that they differ in low-molecular weight fragments of 8, 5, 4.5, 4 and 3 kDa, respectively.
Schraven
B
B
Angewandte Immunologie, Deutsches Krebsforschungszentrum, Heidelberg, FRG.
Schirren
A
A
Kirchgessner
H
H
Siebert
B
B
Meuer
S C
SC
D015703:Antigens, CD / Q000032:analysis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology; D018801:CD2 Antigens; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000032:analysis; D006649:Histocompatibility Antigens / Q000032:analysis*; D006801:Humans; D017493:Leukocyte Common Antigens; D008213:Lymphocyte Activation; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D010750:Phosphoproteins / Q000032:analysis*; D011505:Protein-Tyrosine Kinases / Q000032:analysis*; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D011971:Receptors, Immunologic / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology*
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D006649:Histocompatibility Antigens; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D011971:Receptors, Immunologic; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D017493:Leukocyte Common Antigens; D019204:GTP-Binding Proteins