partial sequences for a novel mammalian calcium channel subunit which we have labeled as the α 1i subunit , and an additional novel human calcium channel which we have labeled as the α 1h subunit are provided . knowledge of the sequence of these two calcium channels permits the localization and recovery of the complete sequence from human cells , and the development of cell lines which express the novel calcium channels of the invention . these cells may be used for identifying compounds capable of acting as agonists or antagonists to the calcium channels .