Mutations in the non-catalytic domains of Fyn and Fgr tyrosine kinases reveal differences in mechanisms of their regulation.

: Non-catalytic domains of tyrosine kinases from the Src family are believed to be regulated intra- and intermolecularly through protein-protein interactions. We have deleted the SH2 and SH3 domains from Fyn and Fgr and have generated two point mutations in residues completely conserved in all members of the Src family. The dramatically different biological effects of these mutations suggest that non-catalytic domains regulate Src family kinase activities through distinctly different mechanisms.