[Term]
id: PR:000000673
name: cyclic nucleotide-gated channel alpha subunit
def: "A cyclic nucleotide-regulated channel protein that has amino- and carboxyl-terminal intracellular domains separated by a domain (common with other ion channels) containing six transmembrane helices (S1-S6) in which the last two helices (S5 and S6) flank a loop, called the pore loop, which determines ion selectivity. The carboxy-terminal region contains the Cyclic nucleotide-binding domain (Pfam:PF00027) (CNBD) and a region connecting the CNBD to the S6 segment (C-linker), which is important for modulation by transition metals. In addition, CNG alpha has a carboxy-terminal leucine zipper that seems to be involved in inter-subunit interaction. CNG alpha subunits combine with the beta subunits to form the cyclic nucleotide-gated ion channels, which mediate sensory transduction in photoreceptors and olfactory sensory neurons. These channels are likely composed of four subunits around a centrally located ion-permeable pore that opens in response to the direct binding of intracellular cyclic nucleotides. CNG channels are non-selective cation channels. They are not gated by membrane voltage although their structure includes the transmembrane S4 motif known to function as the membrane voltage sensor in all voltage-gated ion channels, but it has been shown to be important for proper folding and processing. Alpha and beta subunits of the CNG channel are very similar, however only alpha subunits are able to homooligomerize and form functional channels." [PMID:12432397, PRO:CNA]
comment: Category=family.
xref: PIRSF:PIRSF002403
is_a: PR:000044648 ! cyclic nucleotide-regulated channel protein