Human Protein Tyrosine Phosphatase Receptor Type K (PTPRK) Protein

Background

PTPRK is a receptor-type protein tyrosine phosphatase involved in cell adhesion, contact inhibition, and tumor suppression. Structurally, it consists of an extracellular region with multiple immunoglobulin-like (Ig) and fibronectin type III domains, a single transmembrane domain, and two intracellular phosphatase domains, where the first is catalytically active. PTPRK is predominantly expressed in epithelial tissues and the immune system. It plays a key role in regulating β-catenin signaling, which is critical for maintaining cell adhesion and inhibiting proliferation. PTPRK has been identified as a tumor suppressor, and its downregulation or loss has been associated with colorectal, lung, and breast cancers. It also participates in immune cell development, particularly T-cell maturation. By dephosphorylating key tyrosine kinases and adhesion molecules, PTPRK maintains cellular homeostasis and tissue integrity.