The function of GRIK5 (glutamate ionotropic receptor kainate type subunit 5, Ensembl gene identifier ENSG00000105737) is as follows. Ionotropic glutamate receptor that functions as a cation- permeable ligand-gated ion channel, gated by L-glutamate and the glutamatergic agonist kainic acid. Cannot form functional channels on its own and produces channel activity only in heteromeric assembly with GRIK1 and GRIK2 subunits (PubMed:1321949, PubMed:14511640, PubMed:8730589). Can form functional heteromeric receptors with GRIK3 (By similarity). {ECO:0000250|UniProtKB:Q63273, ECO:0000269|PubMed:1321949, ECO:0000269|PubMed:14511640, ECO:0000269|PubMed:8730589}.