q-type calcium channel q-type calcium channel the q-type calcium channel is a type of voltage-dependent calcium channel. like the others of this class, the α1 subunit is the one that determines most of the channel's properties. calcium channel, voltage-dependent, p/q type, alpha 1a subunitidentifierssymbolcacna1aalt. symbolscacnl1a4, sca6, mhp1, mhpiuphar532ncbi gene773hgnc1388omim601011refseqnm_000068uniproto00555other datalocuschr. 19 p13search forstructuresswiss-modeldomainsinterpro they are poorly understood, but like r-type calcium channels, they appear to be present in cerebellar granule cells. they have a high threshold of activation and relatively slow kinetics.