BOTH SH2 DOMAINS ARE INVOLVED IN INTERACTION OF SHP-1 WITH THE EPIDERMAL GROWTH-FACTOR RECEPTOR BUT CANNOT CONFER RECEPTOR-DIRECTED ACTIVITY TO SHP-1 SHP-2 CHIMERA/

The previously demonstrated functional and physical interaction of the SH2 domain protein-tyrosine phosphatase SHP-1 with the epidermal grow th factor (EGF) receptor (Tomic, S,, Greiser, U,, Lammers, R,, Kharito nenkov, A, Imyanitov, E,, Ullrich, A, and Bohmer, F. D, (1995) J, Biol , Chem 270, 21277-21284) was investigated with respect to the involved structural elements of SHP-1, Various mutants of SHP-1 were transient ly expressed in 293 or COS-7 cells and analyzed for their capacity to associate with immobilized autophosphorylated EGF receptor in vitro an d to dephosphorylate coexpressed EGF receptor in intact cells, inactiv ating point mutation of the C-terminal SH2 domain reduced the associat ion weakly, point mutation of the N-terminal SH2 domain reduced associ ation strongly and the respective double mutation abolished associatio n totally. The capacity of SHP-1 to dephosphorylate coexpressed EGF re ceptor was impaired by all point mutations, Truncation of the N-termin al or of both SH2 domains strongly reduced or abolished association, r espectively, but the truncated SHP-1 derivatives still dephosphorylate d coexpressed EGF receptor effectively. Various chimeric protein-tyros ine phosphatases constructed from SHP-1 and the closely homologous SHP -2 dephosphorylated the EGF receptor when they contained the catalytic domain of SHP-1, As native SHP-2, the chimera lacked activity toward the receptor when they contained the catalytic domain of SHP-2, despit e their capacity to associate with the receptor and to dephosphorylate an artificial phosphopeptide. We conclude that the differential inter action of SHP-1 and SHP-2 with the EGF receptor is due to the specific ity of the respective catalytic domains rather than to the specificity of the SH2 domains, Functional interaction of native SHP-1 with the E GF receptor requires association mediated by both SH2 domains.