Assignment of the protein-tyrosine phosphatase beta gene (PTPRB) to cattle chromosome 5q23→q24 by in situ hybridization and somatic cell panel analysis

Protein tyrosine phosphatases, together with protein tyrosine kinases, regulate the tyrosine phosphorylation that controls cell activities and proliferation. PTPRB contains an extracellular domain, a single transmembrane segment and one intracytoplasmic catalytic domain, hence it belongs to receptor type protein tyrosine phosphatases. The extracellular region of PTPRB is composed of multiple fibronectin type-3 repeats, which was shown to interact with neuronal receptor and cell adhesion molecules, such as contactin (Rios et al., 2000) and tenascin C (Adamsky et al., 2001, 2003). Expression analysis implicate the roles of PTPRB in cell adhesion, neurite growth, and neuronal differentiation (Nagata et al., 2003). In cattle cell lines, protein tyrosine phosphatases and their substrates were suggested to regulate adherens junctional integrity, the movement of macromolecules and cells through the endothelial paracellular pathway, and capillary tube stability, thus possibly being involved in the immune response (Young et al., 2003). PTPRB was also found to interact with ATP-gated ion channels in the plasma membrane, and may regulate channels by altering their tyrosine phosphorylation status (Ratcliffe et al., 2000; Kim et al., 2001). It provides a component in cell-cell and cell-extracellular matrix signaling events (Garwood et al., 2003). In human PTPRB was mapped previously to HSA12q15→ q21 by FISH (Harder et al., 1992).