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Cloning, Chromosomal Localization and Functional Expression of the Gene Encoding the α‐Subunit of the cG‐MP‐Gated Channel in Human Cone Photoreceptors
Author(s) -
Wissinger Bernd,
Müller Frank,
Weyand Ingo,
Schuffenhauer Simone,
Thanos Solon,
Kaupp U. Benjamin,
Zrenner Eberhart
Publication year - 1997
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1997.tb01680.x
Subject(s) - cloning (programming) , protein subunit , encoding (memory) , gene , biology , channel (broadcasting) , cone (formal languages) , genetics , microbiology and biotechnology , neuroscience , computer science , algorithm , telecommunications , programming language
Cyclic nucleotide‐gated (CNG) ion channels serve as final targets of signal transduction in vertebrate photoreceptors. While the basic mechanisms of phototransduction are similar in rod and cone photoreceptors, both cell types express distinct sets of components of the transduction pathway. We report here the cloning of the cDNA encoding the α‐subunit of the cGMP‐gated channel of human cone photoreceptors. The open reading frame predicts a polypeptide of 694 amino acid residues with conserved functional parts and amino acid positions typical for the α‐subunit of CNG‐channels. Heterologous expression of the cDNA in Xenopus oocytes gave rise to cGMP‐gated channel activity. Antiserum directed against the C‐terminus of the bovine cone CNG channel α‐subunit crossreacted specifically with the heterologously expressed polypeptide and stained cone photoreceptors and weakly also the outer plexiform layer in human retinal sections. Northern blot analysis detected a prominent mRNA species of ∼3.8 kb in human retina. The entire gene spans ∼30 kb of genomic sequence and is located on the pericentric band q11.2 of human chromosome 2. The gene is composed of seven exons, with introns located at positions which are preserved with respect to the human rod gene, indicating a common ancestral gene structure. RT‐PCR analysis gave no evidence for alternatively spliced transcripts.