A genome-wide survey of human tyrosine phosphatases

Tyrosine phosphatases play an important role in cellular signalling and networking that is antagonistic to the kinases. Near completion of the human genome- sequencing project permits us to review the distribution of this family and study its involvement in different pathways. Ninety-six homologues of the classical and dual- specific tyrosine phosphatases (DuSPs) were identified in the human genome using sensitive sequence search techniques. Uncommon domain architectures were encountered, including an example where a kinase and a phosphatase domain are found to co-exist in a single polypeptide. The evolutionary rate is higher for the DuSP compared with the classical tyrosine phosphatases. Orthologues of the 96 putative human tyrosine phosphatases were identified in four model organisms to study the conservation of the family members. Three nuclear localized tyrosine phosphatases retain an orthologous relationship with all model systems considered but still differ in their domain architectures. The diversity in the multi-domain members of the superfamily occurs mainly through domain recruitment, especially in receptor tyrosine phosphatases. The curation of human tyrosine phosphatases provides a convenient framework for characterizing and analysing the functional and structural properties of this diverse family of proteins.