Platyhelminth voltage-gated calcium channel beta subunit (Cavβ) (Cavβ)

Platyhelminth voltage-gated calcium channel beta subunits (Cavβ) are essential auxiliary proteins that regulate the activity, gating kinetics, and membrane trafficking of the pore-forming alpha-1 subunits in flatworms (Kohn et al., 2001, PubMed: 11445021). These subunits are characterized by their diversity, with specific 'variant' isoforms (such as Smβ_var) being unique to the Platyhelminthes phylum and structurally distinct from mammalian counterparts (Greenberg, 2005, PubMed: 15933155). These variant subunits have long been identified as the primary molecular target for Praziquantel, the most widely used drug for treating schistosomiasis and other trematode infections. Praziquantel is thought to bind to the Cavβ subunit, inducing a conformational change that promotes the opening of the calcium channel complex and results in a massive influx of calcium ions into the parasite's cells (Jeziorski & Greenberg, 2006, PubMed: 16707643). This sudden increase in intracellular calcium triggers rapid and sustained muscle contraction, leading to spastic paralysis, and causes significant damage to the parasite's tegument (Park & Marchant, 2020, PubMed: 32810105). The resulting tegumental vacuolization exposes parasite antigens to the host's immune system, facilitating the clearance of the infection. Despite the success of Praziquantel, the reliance on a single drug target raises concerns about the development of resistance, and the subunit's role in different life stages of the parasite remains a key area of research (Pica-Mattoccia et al., 2007, PubMed: 17210194).

Other names

Smβ_varSmβ2Voltage-dependent calcium channel subunit betaPraziquantel-sensitive calcium channel beta subunitPlatyhelminth voltage-gated Ca2+ channel β subunitsbetavar variants)

Praziquantel acts as an allosteric modulator that binds to the beta subunit, specifically the variant isoforms, inducing a conformational change that promotes the opening of the calcium channel complex and results in massive calcium influx.