1.A.84.1.10
CALHM1 of 346 aas and 4 or 5 TMSs.  A  cryo-EM structure of full-length Ca²⁺-free CALHM1 from Danio rerio at an overall resolution of 3.1 Å has been published (Ren et al. 2020). The structure reveals an octameric architecture with a wide pore diameter of ~20 Å, presumably representing the active conformation. The structure is substantially different from that of the isoform CALHM2, which forms both undecameric hemichannels and gap junctions. The N-terminal small helix folds back to the pore and forms an antiparallel interaction with TMS 1. Structural analysis revealed that the extracellular loop 1 region within the dimer interface may contribute to oligomeric assembly. A positive potential belt inside the pore was identified that may modulate ion permeation (Ren et al. 2020).