The Ascidian Dihydropyridine-Resistant Calcium Channel as the Prototype of Chordate L-Type Calcium Channel

This review describes recent findings on voltage-gated Ca channel (Cav channel) cloned from ascidians, the most primitive chordates. Ascidian L-type like Cav channel has several unusual features: (1) it is closely related to the prototype of chordate L-type Cav channels by sequence alignment; (2) it is resistant to dihydropyridine due to single amino acid change in the pore region, and (3) maternally provided RNA putatively encodes a truncated protein which has remarkable suppressive effect on Cav channel expression during development. Ascidian Cav channel will provide a useful molecular clue in the future to understand Ca2+-regulated cell differentiation and physiology with the background of recently defined ascidian genome and molecular biological tools.