TABLE 3

CNGA3 channels

Channel name CNGA31,2,3,4,5
Description Cyclic nucleotide-gated cation channel A subunit
Other names CNG3, CNGa2, CCNC1
Molecular information Human: 694aa, NM_001298, NP_001298, chr. 2q11.2
Rat: 611aa, NM_053495, NP_445947, chr. 9q21
Mouse: 631aa, NM_009918, NP_034048, chr. 1 B
Associated subunits CNGB3 (cone photoreceptor channel: 2 CNGA3:2 CNGB3)
Functional assays Patch-clamp, calcium imaging
Current Cyclic nucleotide-activated current
Conductance 40pS
Ion selectivity Ca2+ > K+ ∼ Na+
Activation Not established
Inactivation Not established
Activators cGMP » cAMP (partial agonist)
Gating modifiers None
Blockers l-cis-diltiazem (in the presence of CNGB3)
Radioligands None
Channel distribution Cone photoreceptor, subpopulation of olfactory neurones, some central neurones, pinealocytes, sperm
Physiological functions Light transduction (daylight, color vision)
Mutations and pathophysiology Missense mutations in CNGA3 cause achromatopsia (rod monochromacy) and retinal degeneration
Pharmacological significance Not established
  • aa, amino acids; chr., chromosome.

  • 1. Biel M, Zong X, Distler M, Bosse E, Klugbauer N, Murakami M, Flockerzi V, and Hofmann F (1994) Another member of the cyclic nucleotide-gated channel family, expressed in testis, kidney, and heart. Proc Natl Acad Sci USA 91:3505-3509

  • 2. Bonigk W, Altenhofen W, Muller F, Dose A, Illing M, Molday RS, and Kaupp UB (1993) Rod and cone photoreceptor cells express distinct genes for cGMP-gated channels. Neuron 10:865-877

  • 3. Hirano AA, Hack I, Wassle H, and Duvoisin RM (2000) Cloning and immuno cytochemical localization of a cyclic nucleotide-gated channel alpha-subunit to all cone photoreceptors in the mouse retina. J Comp Neurol 421:80-94

  • 4. Weyand I, Godde M, Frings S, Weiner J, Muller F, Altenhofen W, Hatt H, and Kaupp UB (1994) Cloning and functional expression of a cyclic-nucleotide-gated channel from mammalian sperm. Nature (Lond) 368:859-863

  • 5. Yu WP, Grunwald ME, and Yau KW (1996) Molecular cloning, functional expression and chromosomal localization of a human homolog of the cyclic nucleotide-gated ion channel of retinal cone photoreceptors. FEBS Lett 393:211-215