Protein tyrosine phosphatase receptor type N (PTPRN)

Protein tyrosine phosphatase receptor type N (PTPRN), also known as IA-2 or ICA512, is a transmembrane protein uniquely expressed in neuroendocrine tissues such as pancreatic islets, hypothalamus, and pituitary. PTPRN is structurally part of the receptor-type protein tyrosine phosphatase (PTPR) family, featuring an extracellular domain, a single transmembrane domain, and a cytosolic domain; however, due to critical mutations, it lacks phosphatase enzymatic activity and is thus classified as a pseudophosphatase. Rather than catalyzing dephosphorylation, PTPRN is involved in the regulation of secretory vesicle exocytosis, particularly influencing insulin storage and release from beta cells and modulating neuroendocrine gene expression and cell proliferation. It was first identified as an autoantigen in type 1 diabetes, where autoantibodies against IA-2 are established biomarkers for autoimmune destruction of pancreatic beta cells. PTPRN's role in disease is currently most prominent in diabetes autoimmunity, although emerging evidence suggests possible involvement in some cancers (glioma, metastatic cancers) and neuroendocrine dysregulation.

Other names

IA-2ICA512Islet cell antigen 512Insulinoma-associated tyrosine-phosphatase-like proteinPTP IA-2R-PTP-NICA 512ICA512-NTFICA512-TMFICA512-CCFIslet cell antigen 2Islet cell autoantigen 3PTPLPBEM-3mKIAA4064ICA105IA-2/PTP

Not applicable for classic pharmacological targeting; however, autoantibodies against PTPRN mediate beta-cell autoimmunity in type 1 diabetes.