| Author: | Lerea-C-L. Bunt-Milam-A-H. Hurley-J-B. |
| Title: | Alpha transducin is present in blue-, green-, and red-sensitive
cone photoreceptors in the human retina. |
| Source: | Neuron. 1989 Sep. 3(3). P 367-76. |
| Abstract: | Phototransduction in vertebrate rod and cone photoreceptor
cells involves G protein-mediated light stimulation of cGMP
hydrolysis. Enzymes of the cGMP hydrolysis cascades of rods and
cones are products of different genes. Three different classes
of cones in the human retina are maximally sensitive to either
blue, green, or red light. Distinct opsin genes are expressed
in each type of cone. The distribution of cone types in human
retina was determined using anti-peptide antibodies that
recognize specific amino acid sequences in green/red opsin and
blue opsin. These antibodies together with an anti-peptide
antibody against Tc alpha were used in double labeling
experiments to demonstrate the presence of the Tc alpha peptide
in all types of cones. cDNA clones corresponding to human rod
and cone transducin alpha subunit (Tr alpha and Tc alpha) genes
were isolated. Southern blot analyses of human genomic DNA
suggest that there is only one rod T alpha gene but more than
one cone T alpha gene. The multiple Tc alpha genes could be
closely related genes or different Tc alpha alleles, or one
could be a pseudogene. |
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