Can bidirectionally induce pre- and post-synaptic differentiation of neurons by mediating interaction with IL1RAP and IL1RAPL1 trans-synaptically (PubMed:25908590). Involved in pre-synaptic differentiation through interaction with SLITRK2 (PubMed:25989451). H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate Interacts with PPFIA1, PPFIA2 and PPFIA3 (By similarity). Interacts (via extracellular domain) with SLITRK4 (via LRR 1 and 2 repeats) (PubMed:25989451). Interacts with SLITRK2; induces presynaptic differentiation (PubMed:25989451). Interacts (via the second immunoglobilin domain) with IL1RAPL1 (via the first immunoglobilin domain); induces pre- and postsynaptic differentiation of neurons and synapse formation. Isoform G, isoform H, isoform I, isoform J, and isoform K do not interact with IL1RAPL1 (PubMed:25908590, PubMed:21940441). Interacts (via the third immunoglobilin domain) with IL1RAP (via the first immunoglobilin domain); induces pre- and postsynaptic differentiation of neurons (PubMed:25908590). Additional isoforms seem to exist. Brain, kidney, heart, and some B-cell lines. A cleavage occurs, separating the extracellular domain from the transmembrane segment. This process called 'ectodomain shedding' is thought to be involved in receptor desensitization, signal transduction and/or membrane localization (By similarity). Belongs to the protein-tyrosine phosphatase family. Receptor class 2A subfamily. Extended N-terminus.