Regulates voltage-gated potassium channels assembled from KCNA1, KCNA4 and KCNAB1. It slows down channel inactivation by precluding channel closure mediated by the KCNAB1 subunit. Ligand for ADAM22 that positively regulates synaptic transmission mediated by AMPA-type glutamate receptors (By similarity). Plays a role in suppressing the production of MMP1/3 through the phosphatidylinositol 3-kinase/ERK pathway. May play a role in the control of neuroblastoma cell survival. Oligomer. Interacts with KCNA1 within a complex containing KCNA1, KCNA4 and KCNAB1. Part of a complex containing ADAM22, DLG4/PSD95 and CACNG2/Stargazin (PubMed:27066583). Can bind to ADAM11 and ADAM23. Isoform 1 but not isoform 2 is secreted. Isoform 1 is enriched in the Golgi apparatus while isoform 2 accumulates in the endoplasmic reticulum. Predominantly expressed in neural tissues, especially in brain. Expression is reduced in low-grade brain tumors and significantly reduced or absent in malignant gliomas. Isoform 1 is absent in the cerebellum and is detectable in the occipital cortex and hippocampus; higher amounts are observed in the parietal and frontal cortices, putamen, and, particularly, in the temporal neocortex, where it is 3.5 times more abundant than in the hippocampus (at protein level). Isoform 3 shows the highest expression in the occipital cortex and the lowest in the hippocampus (at protein level). Down-regulated in neuroblastoma cells. Glycosylated. The disease is caused by variants affecting the gene represented in this entry.