PTP-like domain of receptor-type tyrosine-protein phosphatase S, repeat 2
Receptor-type tyrosine-protein phosphatase S (PTPRS), also known as receptor-type tyrosine-protein phosphatase sigma (R-PTP-sigma), belongs to the LAR (leukocyte common antigen-related) family of receptor-type tyrosine-protein phosphatases (RPTPs), which belong to the larger family of classical tyrosine-specific protein tyrosine phosphatases (PTPs). PTPs (EC 3.1.3.48) catalyze the dephosphorylation of phosphotyrosine peptides. PTPRS is a receptor for glycosaminoglycans, including heparan sulfate proteoglycan and neural chondroitin sulfate proteoglycans (CSPGs), which present a barrier to axon regeneration. It also plays a role in stimulating neurite outgrowth in response to the heparan sulfate proteoglycan GPC2. PTPRS contains an extracellular region with three immunoglobulin-like (Ig) domains and four to eight fibronectin type III (FN3) repeats (determined by alternative splicing), a single transmembrane domain, followed by an intracellular region with a membrane-proximal catalytic PTP domain (repeat 1, also called D1) and a membrane-distal non-catalytic PTP-like domain (repeat 2, also called D2). This model represents the non-catalytic PTP-like domain (repeat 2). Although described as non-catalytic, this domain contains the catalytic cysteine and the active site signature motif, HCSAGxGRxG.
Feature 1: catalytic site [active site], 2 residue positions
Conserved feature residue pattern:C R
Evidence:
Comment:this second PTP domain is expected to be inactive, but it contains the catalytic cysteine
Comment:the catalytic cysteine initiates a nucleophilic attack on the phosphate group of the substrate, forming a transient phosphoenzyme intermediate and releasing the substrate dephosphorylated; the transition state is stabilized by the arginine present in the catalytic pocket
Jiyao W et al.(2023). "The conserved domain database in 2023.",