Phosphatase Subfamily PTPRK

Phosphatase Classification: Fold CC1:Superfamily CC1: Family PTP: Subfamily PTPRK

PTPRG is a receptor PTP family involved in metazoan neural development and maybe cancer.

Evolution

PTPRK subfamily is vertebrate specific. There are four copies in human.

Domain Structure

PTPRK has dual intracellular catalytic domains. The canonical extracellular domain combination is a MAM domain, Ig domain and multiple FN3 domain.

MAM domain is essential for homophilic cell-cell interaction and helps determine the specificity of these interactions. Truncated PTPRM is properly expressed at the cell surface but fails to promote cell-cell adhesion. Homophilic cell adhesion is fully restored in a chimeric PTPRM molecule containing the MAM domain of PTPRK. However, this chimeric RPTP mu does not interact with either PTPRK or PTPRM [1].

Functions

PTPRK and PTPRM mediates homophilic cell-cell interaction [1, 2].

PTPRK

PTPRK is a putative tumor suppressor [3]. PTPRK influences transactivating activity of beta-catenin in non-tumoral and neoplastic cells by regulating the balance between signaling and adhesive beta-catenin which is a molecule endowed with a dual function being involved both in cell adhesion and in Wnt signaling pathway [4].

PTPRK dephosphorylates EGFR and thereby regulates Epidermal growth factor receptor (EGFR) tyrosine phosphorylation and subsequent promotes human keratinocyte survival and proliferation [5]. On the other hand, transforming growth factor-beta1 upregulates the expression of PTPRK [6].

PTPRK regulates CD4+ T cell development through ERK1/2-mediated signaling [7].

References

1. Zondag GC, Koningstein GM, Jiang YP, Sap J, Moolenaar WH, and Gebbink MF. Homophilic interactions mediated by receptor tyrosine phosphatases mu and kappa. A critical role for the novel extracellular MAM domain. J Biol Chem. 1995 Jun 16;270(24):14247-50. DOI:10.1074/jbc.270.24.14247 |
2. Sap J, Jiang YP, Friedlander D, Grumet M, and Schlessinger J. Receptor tyrosine phosphatase R-PTP-kappa mediates homophilic binding. Mol Cell Biol. 1994 Jan;14(1):1-9. DOI:10.1128/mcb.14.1.1-9.1994 |
3. Zhang Y, Siebert R, Matthiesen P, Yang Y, Ha H, and Schlegelberger B. Cytogenetical assignment and physical mapping of the human R-PTP-kappa gene (PTPRK) to the putative tumor suppressor gene region 6q22.2-q22.3. Genomics. 1998 Jul 15;51(2):309-11. DOI:10.1006/geno.1998.5323 |
4. Xu Y, Tan LJ, Grachtchouk V, Voorhees JJ, and Fisher GJ. Receptor-type protein-tyrosine phosphatase-kappa regulates epidermal growth factor receptor function. J Biol Chem. 2005 Dec 30;280(52):42694-700. DOI:10.1074/jbc.M507722200 |
5. Xu Y, Tan LJ, Grachtchouk V, Voorhees JJ, and Fisher GJ. Receptor-type protein-tyrosine phosphatase-kappa regulates epidermal growth factor receptor function. J Biol Chem. 2005 Dec 30;280(52):42694-700. DOI:10.1074/jbc.M507722200 |
6. Yang Y, Gil M, Byun SM, Choi I, Pyun KH, and Ha H. Transforming growth factor-beta1 inhibits human keratinocyte proliferation by upregulation of a receptor-type tyrosine phosphatase R-PTP-kappa gene expression. Biochem Biophys Res Commun. 1996 Nov 21;228(3):807-12. DOI:10.1006/bbrc.1996.1736 |
7. Erdenebayar N, Maekawa Y, Nishida J, Kitamura A, and Yasutomo K. Protein-tyrosine phosphatase-kappa regulates CD4+ T cell development through ERK1/2-mediated signaling. Biochem Biophys Res Commun. 2009 Dec 18;390(3):489-93. DOI:10.1016/j.bbrc.2009.09.117 |