PTPRH
Description
The PTPRH (protein tyrosine phosphatase receptor type H) is a protein-coding gene located on chromosome 19.
Receptor-type tyrosine-protein phosphatase H is an enzyme that in humans is encoded by the PTPRH gene. The protein encoded by this gene is a member of the protein tyrosine phosphatase (PTP) family. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. This PTP possesses an extracellular region, a single transmembrane region, and a single intracytoplasmic catalytic domain, and thus represents a receptor-type PTP. The extracellular region contains eight fibronectin type III-like repeats and multiple N-glycosylation sites. The gene was shown to be expressed primarily in brain and liver, and at a lower level in heart and stomach. It was also found to be expressed in several cancer cell lines, but not in the corresponding normal tissues.
PTPRH acts as a protein phosphatase, playing a role in regulating cell growth and motility. It achieves this by dephosphorylating focal adhesion-associated substrates, thus negatively influencing integrin-mediated signaling. PTPRH also triggers apoptosis through two distinct pathways: inhibiting survival signaling via PI 3-kinase, Akt, and ILK, and activating a caspase-dependent proapoptotic route. Furthermore, it suppresses LCK activity and its activation by TCR stimulation, ultimately impacting TCR-induced activation of MAP kinase and CD69 surface expression. PTPRH also inhibits the tyrosine phosphorylation of LAT and ZAP70, both crucial players in TCR signaling. Additionally, PTPRH hinders both basal DOK1 activity and its CD2-induced tyrosine phosphorylation. It dephosphorylates BCAR1, focal adhesion kinase, and SRC, ultimately reducing the migratory activity of Jurkat cells. Finally, PTPRH reduces the tyrosine phosphorylation of CEACAM20, thereby contributing to the suppression of the intestinal immune response associated with CEACAM20.
PTPRH is also known as R-PTP-H, SAP1.
