May regulate secretion and presynaptic differentiation through inhibition of the activity of N-type voltage-gated calcium channel (PubMed:12783849). May activate the MAP kinase JNK (PubMed:15123616). Plays a role in neurite outgrowth (By similarity). During dendritic spine formation can bidirectionally induce pre- and post-synaptic differentiation of neurons by trans-synaptically binding to PTPRD (By similarity). {ECO:0000250|UniProtKB:P59823, ECO:0000250|UniProtKB:P59824, ECO:0000269|PubMed:12783849, ECO:0000269|PubMed:15123616}. This is the function of ENSG00000169306 (IL1RAPL1, interleukin 1 receptor accessory protein like 1).