Abstract

SHP-1 is a protein-tyrosine phosphatase associated with inhibition of activation pathways in hematopoietic cells. The catalytic activity of SHP-1 is regulated by its two SH2 (Src homology 2) domains; phosphotyrosine peptides that bind to the SH2 domains activate SHP-1. The consensus sequence (I/V)XYXX(L/V) is present in the cytoplasmic tails of several lymphocyte receptors that interact with the second SH2 domain of SHP-1. In several of these receptors, there are two or three occurrences of the motif. Here we show that the conserved hydrophobic amino acid preceding the phosphotyrosine is critical for binding to and activation of SHP-1 by peptides corresponding to sequences from killer cell inhibitory receptors. The interaction of most SH2 domains with phosphopeptides requires only the phosphotyrosine and the three residues downstream of the tyrosine. In contrast, the shortest peptide able to bind or activate SHP-1 also included the two residues upstream of the phosphotyrosine. A biphosphopeptide corresponding to the cytoplasmic tail of a killer cell inhibitory receptor with the potential to interact simultaneously with both SH2 domains of SHP-1 was the most potent activator of SHP-1. The hydrophobic residue upstream of the tyrosine was also critical in the context of the biphosphopeptide. The contribution of a hydrophobic amino acid two residues upstream of the tyrosine in the SHP-1-binding motif may be an important feature that distinguishes inhibitory receptors from those that provide activation signals.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.