Voltage-sensor protein present on the post-synaptic side of glutamatergic mossy fibers and granule cells in the cerebellum (PubMed:25165868, PubMed:30810529). Despite the presence of a voltage- sensor segment, does not form a functional ion channel and its precise role remains unclear (PubMed:25165868, PubMed:30810529). Undergoes both rapid and slow structural rearrangements in response to changes in voltage (PubMed:30810529). Contains a zinc-binding site that can regulate the slow conformational transition (PubMed:30810529). . This is the function of TMEM266 (transmembrane protein 266, Ensembl gene identifier ENSG00000169758).