Glutamate-gated chloride channel subunit alpha-3B (GluClα3B) (GluClα3B)

The Haemonchus contortus Glutamate-gated chloride channel subunit alpha-3B (GluClα3B) is a critical component of the inhibitory nervous system in the parasitic nematode Haemonchus contortus, commonly known as the barber's pole worm. This protein belongs to the Cys-loop superfamily of ligand-gated ion channels and is unique to invertebrates, which allows for the selective targeting of parasites without affecting the vertebrate host (Wolstenholme, 2012). GluClα3B subunits assemble into pentameric channels that regulate chloride ion flow across neuronal and muscle cell membranes in response to the neurotransmitter glutamate (McCavera et al., 2007). These channels are the primary molecular targets for macrocyclic lactone anthelmintics, such as ivermectin, which bind allosterically to the channel's transmembrane domain (Forrester et al., 2003). The binding of these drugs causes the channel to remain open, leading to a persistent influx of chloride ions that hyperpolarizes the cell and results in flaccid paralysis of the worm's pharyngeal and somatic muscles (Smith et al., 2009). This paralysis prevents the parasite from feeding and maintaining its position within the host's abomasum, ultimately leading to its death. Due to the extensive use of macrocyclic lactones in livestock, mutations in the glc-3 gene encoding this subunit are frequently investigated as key drivers of anthelmintic resistance (McCavera et al., 2009).

Other names

GLC-3BHco-GLC-3BGlutamate-gated chloride channel alpha 3 subunitHco-glc-3b

Macrocyclic lactones act as potent allosteric activators of the glutamate-gated chloride channel. By binding to the transmembrane domain, they stabilize the open state of the channel, leading to a persistent influx of chloride ions, membrane hyperpolarization, and subsequent flaccid paralysis of the parasite (Wolstenholme, 2012; McCavera et al., 2007).