Evidence for involvement of glycoprotein-CD45 phosphatase in reversing glycoprotein-CD3-induced microtubule-associated protein-2 kinase activity in Jurkat T-cells.
Ligation of CD3/TCR on T-cells induces transient activation of lymphoid MAP-2 kinase (MAP-2K), a 43 kDa serine kinase which itself is a substrate of an unidentified tyrosine kinase (pp43). The reversibility of the MAP-2K response agrees with removal of tyrosine phosphates from pp43. Since both activity as well as tyrosine phosphorylation of MAP-2K could be prolonged by Na3VO4, a phosphotyrosine phosphatase inhibitor, we studied the effect of the common CD45 isoform, which is a member of the CD45 phosphatase family, on MAP-2K activity in vivo and in vitro. We demonstrate the ability of purified CD45 phosphatase to remove tyrosine phosphates from partially purified lymphoid MAP-2K. Utilizing the approach of heterologous receptor aggregation, we also showed that CD45 could inhibit the induction of MAP-2K activity in intact Jurkat cells during CD3 or CD3 + CD4 stimulation. We therefore suggest that this phosphatase may control the activity of lymphoid MAP-2K in vivo.
Pollack
S
S
Department of Microbiology and Immunology, UCLA School of Medicine 90024-1680.
Ledbetter
J A
JA
Katz
R
R
Williams
K
K
Akerley
B
B
Franklin
K
K
Schieven
G
G
Nel
A E
AE
D015703:Antigens, CD / Q000502:physiology; D000943:Antigens, Differentiation / Q000502:physiology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D017252:CD3 Complex; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D004789:Enzyme Activation; D006649:Histocompatibility Antigens / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D017493:Leukocyte Common Antigens; D008870:Microtubules / Q000201:enzymology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D011494:Protein Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013601:T-Lymphocytes; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D015703:Antigens, CD; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D006649:Histocompatibility Antigens; D011948:Receptors, Antigen, T-Cell; D019000:Phosphotyrosine; D014443:Tyrosine; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D017493:Leukocyte Common Antigens; D002118:Calcium