The molecular biology of invertebrate voltage-gated Ca2+ channels

The importance of voltage-gated Ca2+ channels in cellular function is illustrated by the many distinct types of Ca2+ currents found in vertebrate tissues, a variety that is generated in part by numerous genes encoding Ca2+ channel subunits. The deg;ree to which this genetic diversity is shared by invertebrates has only recently become apparent, Cloning of Ca2+ channel subunits from various invertebrate species, combined with the wealth of information from the Caenorhabditis elegans genome, has clarified the organization and evolution of metazoan Ca2+ channel genes. Functional studies have employed novel structural information gained from invertebrate Ca2+ channels to complement ongoing research on mammalian Ca2+ currents, while demonstrating that the strict correspondence between pharmacological and molecular classes of vertebrate Ca2+ channels does not fully extend to invertebrate tissues. Molecular structures can now be combined with physiological data to develop a more cogent system of categorizing invertebrate channel subtypes, In this review, we examine recent progress in the characterization of invertebrate Ca2+ channel genes and its relevance to the diversity of invertebrate Ca2+ currents.