catalytic domain of tyrosine-protein phosphatase non-receptor type 18
Tyrosine-protein phosphatase non-receptor type 18 (PTPN18), also called brain-derived phosphatase, belongs to the family of classical tyrosine-specific protein tyrosine phosphatases (PTPs). PTPs (EC 3.1.3.48) catalyze the dephosphorylation of phosphotyrosine peptides. PTPN18 regulates HER2-mediated cellular functions through defining both its phosphorylation and ubiquitination states. The N-terminal catalytic PTP domain of PTPN18 blocks lysosomal routing and delays the degradation of HER2 by dephosphorylation, and its C-terminal PEST domain promotes K48-linked HER2 ubiquitination and its destruction via the proteasome pathway.