Voltage-gated calcium channel subunits from platyhelminths: Potential role in praziquantel action

Voltage-gated calcium (Ca2+) channels provide the pathway for Ca2+ influxes that underlie Ca2+-dependent responses in muscles, nerves and other excitable cells. They are also targets of a wide variety of drugs and toxins. Ca2+ channels are multisubunit protein complexes consisting of a pore-forming a, subunit and other modulatory subunits, including the beta subunit. Here, we review the structure and function of schistosome Ca2+ channel subunits, with particular emphasis on variant Ca2+ channel beta subunits (Ca-nu beta var) found in these parasites. In particular, we examine the role these beta subunits may play in the action of praziquantel, the current drug of choice against schistosomiasis. We also present evidence that Ca-nu beta var homologs are found in other praziquantel-sensitive platyhelminths such as the pork tapeworm, Taenia solium, and that these variant P subunits may thus represent a platyhelminth-specific gene family. (c) 2006 Australian Society for Parasitology Inc Published by Elsevier Ltd. All rights reserved.