Identification of the alpha-subunits of rod and cone transducin in chicken photoreceptor cells.
The chicken retina has several types of cone photoreceptor cells, each of which contains a visual pigment, chicken red (iodopsin), green, blue or violet. Although biochemical and photochemical properties of these cone pigments have been well characterized, no information is available about the chicken photoreceptor G-protein, transducin, which couples with the visual pigment to convert a photon signal into a cellular response. To identify alpha-subunits of chicken rod and cone transducins (Tr alpha and Tc alpha, respectively), we produced two site-directed antibodies which discriminate between bovine Tr alpha and Tc alpha. Immunohistochemical studies on chicken retinas revealed that the antibody against bovine Tr alpha specifically stained the rod outer segments. On the other hand, the antibody against bovine Tc alpha uniformly stained the outer segments of the double cones and all types of single cones, while the single cones were immunohistochemically classified into three types by using a combination of antibodies against bovine rhodopsin and chicken iodopsin. Immuno-blot analyses demonstrated that the antibody against Tc alpha recognized a single band of chicken photoreceptor protein, whose molecular weight (42,000) was in good agreement with that of bovine Tc alpha (41,000). The antibody against Tr alpha recognized a protein having the same molecular weight as that of bovine Tr alpha (39,000). These observations strongly suggested that all types of chicken cone cells have a single common Tc alpha (42 kDa) structurally related to bovine Tc alpha, though each cone cell type has a distinct visual pigment.
Kokame
K
K
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Fukada
Y
Y
Shichida
Y
Y
Okada
M
M
Honda
Y
Y
Yoshizawa
T
T
D000818:Animals; D002645:Chickens; D015151:Immunoblotting; D007150:Immunohistochemistry; D008970:Molecular Weight; D017948:Retinal Rod Photoreceptor Cells / Q000737:chemistry*; D012374:Rod Cell Outer Segment / Q000737:chemistry; D015293:Transducin / Q000032:analysis*
D015293:Transducin