XB-ART-20399
Neuron
1995 Jan 01;141:177-83. doi: 10.1016/0896-6273(95)90252-x.
Show Gene links
Show Anatomy links
A histidine residue associated with the gate of the cyclic nucleotide-activated channels in rod photoreceptors.
???displayArticle.abstract???
Ion channels directly activated by the binding of cGMP mediate the electrical response to light in rod photoreceptors. Here, we identify a region of the channel associated with the activation gate using potentiation by intracellular Ni2+. Low concentrations of Ni2+ caused a dramatic increase in the response of rod channels expressed in Xenopus oocytes to both cGMP and cAMP. Whereas saturating cAMP normally activated less than 1% of the channels, Ni2+ increased the cAMP potency nearly 50-fold. Ni2+ did not produce potentiation in the related channel from the olfactory epithelium. We localized the Ni(2+)-binding site to a histidine residue in the putative intracellular mouth of the rod channel (H420). We propose a mechanism for potentiation in which Ni2+ binds to H420 primarily when the channel is open, stabilizing the open conformation. These experiments suggest that H420 is associated with the activation gate.
???displayArticle.pubmedLink??? 7530019
???displayArticle.link??? Neuron
???displayArticle.grants???
Genes referenced: camp