Selective activation of G-protein subtypes by vertebrate and invertebrate rhodopsins.
We have quantitatively investigated specificities in activating G-protein subtype by bovine and squid rhodopsins to examine whether or not the phototransduction cascade in each of the photoreceptor cells is determined by the colocalization of a large amount of G-protein subtype (Gt or Gq). In contrast to the efficient activation of respective Gt and Gq, bovine and squid rhodopsins scarcely activated G-protein counterparts. Exchange of alpha- and betagamma-subunits of Gt and Gq indicated the critical role of the alpha-subunit in specific binding to respective rhodopsins. Thus the specific recognition of G-protein subtype by each rhodopsin is a major mechanism in determining the phototransduction cascade.
Terakita
A
A
Department of Biophysics, Graduate School of Science, Kyoto University, Japan.
Yamashita
T
T
Tachibanaki
S
S
Shichida
Y
Y
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D049832:Decapodiformes; D019204:GTP-Binding Proteins / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D012243:Rhodopsin / Q000378:metabolism*; D013997:Time Factors
D011956:Receptors, Cell Surface; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D012243:Rhodopsin; D019204:GTP-Binding Proteins