Receptor-type tyrosine-protein phosphatase delta (R-PTP-delta, also known as PTPRD), 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 () catalyze the dephosphorylation of phosphotyrosine peptides. LAR-RPTPs are synaptic adhesion molecules that play roles in various aspects of neuronal development, including axon guidance, neurite extension, and synapse formation and function [, , ]. PTPRD is involved in pre-synaptic differentiation through interaction with SLITRK2 [, ]. It 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 entry represents the catalytic PTP domain (repeat 1) found in the protein PTPRD from chordates.
