PTPRK

Receptor-type tyrosine-protein phosphatase kappa is an enzyme that in humans is encoded by the PTPRK gene. PTPRK is also known as PTPkappa and PTPκ.

Function

The protein encoded by this gene is a member of the protein tyrosine phosphatase (PTP) family. Protein tyrosine phosphatases are protein enzymes that remove phosphate moieties from tyrosine residues on other proteins. Tyrosine kinases are enzymes that add phosphates to tyrosine residues, and are the opposing enzymes to PTPs. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation.

The human PTPRK gene is located on the long arm of chromosome 6, a putative tumor suppressor region of the genome.

During development

The same reporter construct used by Shen and colleagues, and described above was created by Skarnes et al. during a screen to identify genes important in mouse development. The transgenic mouse was created by combining a β-galactosidase (β-gal) reporter gene with a signal sequence and the transmembrane domain of the type I transmembrane protein CD4. If the transgene was incorporated into a gene with a signal sequence, β-gal activity would remain in the cytosol of the cell and therefore be active. If the reporter gene was incorporated into a gene that lacked a signal sequence, β-gal activity would be in the ER where it would lose β-gal activity. This construct inserted into the phosphatase domain of PTPkappa. Mice generated from these ES cells were viable, suggesting that PTPkappa phosphatase activity is not necessary for embryonic development.