The T-cell antigen CD5 acts as a receptor and substrate for the protein-tyrosine kinase p56lck.

摘要: CD5 is a T-cell-specific antigen which binds to the B-cell CD72 and acts as coreceptor in stimulation of T-cell growth. associates with receptor zeta chain (TcR zeta)/CD3 complex rapidly phosphosphorylated on tyrosine residues result TcR zeta/CD3 ligation. However, despite this, mechanism by generates intracellular signals unclear. In this study, we demonstrate that coupled protein-tyrosine kinase p56lck can act substrate for p56lck. Coexpression baculovirus expression system resulted phosphorylation residues. Further, anti-CD5 anti-p56lck coprecipitated each other variety detergents, including Nonidet P-40 Triton X-100. Anti-CD5 also precipitated from various T cells irrespective or CD4. No binding between p59fyn(T) was detected cells. The induced 10- 15-fold increase catalytic activity, measured vitro analysis. vivo labelling 32P(i) showed four- fivefold Y-394 occupancy when associated CD5. use glutathione S-transferase-Lck fusion proteins precipitation analysis SH2 domain could recognize expressed system. interaction represents novel variant receptor-kinase serve substrate. CD5-p56lck likely play roles signalling T-B collaboration.