SHC BINDING TO NERVE GROWTH-FACTOR RECEPTOR IS MEDIATED BY THE PHOSPHOTYROSINE INTERACTION DOMAIN

Shc is an adaptor protein that contains two phosphotyrosine-binding domains, a Src homology 2 (SH2) domain and the newly described phosphotyrosine interaction (PI) domain. Shc interacts with several tyrosine-phosphorylated proteins and is itself tyrosine-phosphorylated in cells stimulated with a variety of growth factors and cytokines. Upon phosphorylation, Shc binds to the Grb2 . Sos complex leading to the activation of the Ras signaling pathway. Mutational analysis of the nerve growth factor (NGF) receptor (TrkA) suggested that the binding of Shc to the activated receptor is required for NGF-induced neuronal differentiation of PC12 cells. Here we report that the PI domain of Shc directly binds to tyrosine 490 on the autophosphorylated NGF receptor. The PI domain specifically recognizes an I/LXN-PXpY motif (where p indicates phosphorylation) as determined by phosphopeptide competition assay. In addition, the PI domain is able to efficiently compete for binding of full-length Shc proteins to the NGF receptor. In PC12 cells, the Shc SH2 domain interacts with an unidentified tyrosine-phosphorylated protein of 115 kDa but not with the activated NGF receptor. The ability of Shc to interact with different tyrosine-phosphorylated proteins via its PI and SH2 domains may allow Shc to play a unique role in tyrosine kinase signal transduction pathways.