Tyrosine phosphatases SHP-1 and SHP-2 are associated with distinct tyrosine-phosphorylated proteins

SHP-1 and SHP-2 are two SH2 domain-containing tyrosine phosphatases. They share significant overall sequence identity but their functions are often opposite. The mechanism underlying this is not well understood. In this study, we have investigated the association of SHP-1 and SHP-2 with tyrosine-phosphorylated proteins in mouse tissues and in cultured cells treated with a potent tyrosine phosphatase inhibitor, pervanadate. Pervanadate was introduced into mice by intravenous injection. It induced robust tyrosine phosphorylation of cellular proteins in a variety of tissues. Both SHP-1 and SHP-2 were phosphorylated on tyrosyl residues upon pervanadate treatment, and they became associated with distinct tyrosine-phosphorylated proteins in different tissues and cells. Among these proteins, PZR and PECAM were identified as major SHP-2-binding proteins while LAIR-1 was shown to be a major SHP-1-binding protein. A number of other proteins are to be identified. We believe that the different binding proteins may determine the distinct physiological functions of SHP-1 and SHP-2. The present study also provides a general method to induce tyrosine phosphorylation of cellular proteins and to study protein-protein interactions involving tyrosine phosphorylation in vivo and in vitro.