Structure of three high voltage-activated calcium channel alpha1 subunits from Schistosoma mansoni.

Voltage-gated calcium (Ca2+) channels contribute to impulse propagation in excitable cells and also regulate intracellular levels of Ca2+. High voltage-activated (HVA) Ca2+ channels are heteromultimeric membrane proteins. The pore-forming, voltage-sensing subunit is the alpha1 subunit. We have cloned 3 HVA Ca2+ channel alpha1 subunit cDNAs from Schistosoma mansoni. One of these sequences most closely resembles the L-type class of HVA alpha1 subunits. The other two sequences are most closely related to non L-type alpha1 subunits. These schistosome alpha1 subunits have many of the features common to HVA Ca2+ channels, but also have distinct structural motifs. Analysis of the structural and functional properties of schistosome Ca2+ channel subunits may provide information about these critical components of excitable cells.