Structure of three high voltage-activated calcium channel alpha(1) subunits from Schistosoma mansoni

Voltage-gated calcium (Ca2+) channels contribute to impulse propagation in excitable cells and also regulate intracellular levels of Ca2+. High voltag e-activated (HVA) Ca2+ channels are heteromultimeric membrane proteins. The pore-forming, voltage-sensing subunit is the alpha (1) subunit. We have cl oned 3 HVA Ca2+ channel alpha (1) subunit cDNAs from Schistosoma mansoni. O ne of these sequences most closely resembles the L-type class of HVA alpha (1) subunits. The other two sequences are most closely related to non L-typ e al subunits. These schistosome al subunits have many of the features comm on to HVA Ca2+ channels, but also have distinct structural motifs. Analysis of the structural and functional properties of schistosome Ca2+ channel su bunits may provide information about these critical components of excitable cells.