Rod and cone photoreceptor cells express distinct genes for cGMP-gated channels.
Signal transduction in vertebrate rod and cone photoreceptor cells involves ion channels that are directly gated by the internal messenger cGMP. Rods and each type of cones express genetically related yet different forms of photopigments. Enzymes that control the light-stimulated hydrolysis of cGMP in rods and cones are also the product of distinct genes. Two different cDNA clones encoding cGMP-gated channels have been characterized from the chicken retina. Expression of cDNAs in Xenopus oocytes gives rise to cGMP-stimulated channel activity. Antibodies against a synthetic peptide specific for the C-terminal amino acid sequence derived from one clone stain outer segments of cone but not rod photoreceptors. Therefore chicken rod and cone cells each express different forms of cGMP-gated channels that are genetically related to each other. Expression in COS-1 cells produces the complete form of both channel polypeptides, whereas Western blot analysis indicates that channels in outer segment membranes are present in a processed form that is significantly shorter than the full-length polypeptide.
Bönigk
W
W
Institut für Biologische Informationsverarbeitung, Forschungszentrum Jülich, Federal Republic of Germany.
Altenhofen
W
W
Müller
F
F
Dose
A
A
Illing
M
M
Molday
R S
RS
Kaupp
U B
UB
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002645:Chickens; D006152:Cyclic GMP / Q000378:metabolism / Q000494:pharmacology*; D054815:Cyclic Nucleotide-Gated Cation Channels; D004247:DNA / Q000235:genetics; D015870:Gene Expression; D015640:Ion Channel Gating / Q000187:drug effects*; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010786:Photoreceptor Cells / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D014981:Xenopus
D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D012333:RNA, Messenger; D004247:DNA; D006152:Cyclic GMP