Voltage-gated calcium channel beta subunit (Cavbeta) (Cavbeta)

Voltage-gated calcium channels (VGCCs) in schistosomes are essential mediators of calcium signaling, regulating critical processes such as muscle contraction and neuromuscular coordination in the parasite [4, 8]. These channels are heteromultimeric complexes composed of a pore-forming alpha-1 subunit and auxiliary subunits, including a unique variant beta subunit (Cavbeta-var) that is specific to platyhelminths [2, 5]. Unlike conventional vertebrate beta subunits, the schistosome variant subunit (e.g., SmCavbetaA) possesses distinct structural motifs, such as the absence of conserved phosphorylation sites in the beta interaction domain, which modulate the channel's response to pharmacological agents [1, 3]. This variant subunit is a primary molecular target of praziquantel, the gold-standard drug for treating schistosomiasis [6, 10]. Praziquantel interacts with the channel complex to promote a massive influx of calcium ions, resulting in rapid, sustained muscle contraction (paralysis) and disruption of the parasite's tegument [7, 9]. Because this specific beta subunit architecture is absent in humans, it provides a basis for the drug's high selectivity and safety profile [10, 11].

Other names

SmCavbeta-varSmbetaASjbetaVariant calcium channel beta subunitSchistosome calcium channel beta subunitVoltage-operated calcium channel beta subunit

Praziquantel acts as an allosteric modulator of the voltage-gated calcium channel complex containing the variant beta subunit, inducing a conformational change that increases calcium influx, leading to muscle paralysis and tegumental damage.