Abstract
A guanine nucleotide-binding regulatory protein, called transducin or G t couples light-activated rhodopsin with the cGMP phosphodiesterase (Hurley, 1980). Like all G proteins, transducin is a heterotrimer composed of two distinct subunits: αt (39 kDa) and βγt (βt: 36 kDa, γt: 8 kDa). The αt subunit binds GDP and GTP (Fung and Stryer, 1980), and in its GTP-bound form activates the cGMP phosphodiesterase (Fung et al., 1981). The activation is terminated when the bound GTP is hydrolyzed to GDP by an intrinsic GTPase activity (Wheeler and Bitensky, 1977, Fung et al., 1981). Although the βγt subunit does not directly participate in either GTP hydrolysis or phosphodiesterase activation, its presence is important for effective binding of αt to photolyzed rhodopsin and GTP-GDP exchange (Fung, 1983). Transducin binds tightly to photolyzed rhodopsin in intact rod outer segment membranes (Kühn, 1980). It also binds selectively to unphotolyzed rhodopsin in rod outer segment membranes (Hamm et al., 1987) and in reconstituted phospholipid vesicles (Fung, 1983).
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References
Amit, A. G., Mariuzza, R. A., Phillips, S. E. V., and Poljak, R. J., 1986, Three-dimensional structure of an antigen-antibody complex at 2.8 Å resolution, Science, 233:747.
Bradford, M. M., 1976, A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding, Anal. Biochem., 72:248.
Codina, J., Hildebrandt, J. D., Sekura, R. D., Birnbaumer, M., Bryan, J.,Manclark, C. R., Iyengar, R., and Birnbaumer, L., 1984, N s and N i , the stimulatory and inhibitory regulatory components of adenylyl cyclase, J. Biol. Chem., 259:5871.
Deretic, D., and Hamm, H. E., 1987, Topographic analysis of antigenic determinants recognized by monoclonal antibody to the photoreceptor guanyl nucleotide-binding protein, transducin, J. Biol. Chem., 262:10831.
Fung, B. K.-K., and Stryer L., 1980, Photolyzed rhodopsin catalyzes the exchange of GTP for bound GDP in retinal rod outer segments, Proc. Natl. Acad. Sci., 77:2500.
Fung, B. K.-K., Hurley, J. B., and Stryer, L., 1981, Flow of information in the light-triggered cyclic nucleotide cascade of vision, Proc. Natl. Acad. Sci., 78:152.
Fung, B. K.-K., 1983, Characterization of transducin from bovine rod outer segments. I. Separation and reconstitution of the subunits. J. Biol. Chem., 258:10495.
Fung, B. K.-K., and Nash, C. R., 1983, Characterization of transducin from bovine rod outer segments. II. Evidence for distinct binding sites and conformational changes revealed by limited proteolysis with trypsin, J. Biol. Chem., 258:10503.
Hamm, H. E., and Bownds, M., 1984, A monoclonal antibody to guanine nucleotide binding protein inhibits the light-activated cyclic GMP pathway in frog rod outer segment, J. Gen. Physiol., 84:265.
Hamm, H. E., Deretic, D., Hofmann, K. P., Schleicher, A., and Kohl, B., 1987 Mechanism of action of monoclonal antibodies that block the light activation of the guanyl nucleotide-binding protein, transducin, J. Biol. Chem., 262:10831.
Hamm, H. E., Deretic D., Arendt, A., Hargrave P. A., Koening B., Hofman K. P., 1988, Site of G-protein binding to rhodopsin mapped with synthetic peptides from the α subunit, Science, 241:832.
Hurley, J. B., 1980, Isolation and recombination of bovine rod outer segment cGMP phosphodiesterase and its regulators, Biochem. Biophys. Res. Commun., 92:505.
Kleuss, C., Pallat, M., Brendel, S., Rosenthal, W., and Schultz, G., 1987, Resolution of transducin subunits by chromatography on blue sepharose, J. Chrom., 407:281.
Kühn, H., 1980, Light and GTP-regulated interaction of GTPase and other proteins with bovine photoreceptor membranes, Nature, 283:587.
Laemmli, U. K., 1970, Cleavage of structural proteins during the assembly of the head of bacteriophage T4, Nature, 227:680.
Navon, S. E., and Fung, B. K.-K., 1987, Characterization of transducin from bovine retinal rod outer segments, Participation of the amino-terminal region of Ta in subunit interaction, J. Biol. Chem., 262:15746.
Papermaster, D. S., and Dreyer, W, J., 1974, Rhodopsin content in the outer segment membranes of bovine and frog retinal rods, Biochemistry, 13:2438.
Sternweis, P. C., 1986, The purified a subunit of Go and Gi from bovine require βγ for association with phospholipid vesicles, J. Biol. Chem., 261:631.
Watkins, P. A., Burns, D. L., Kanaho, Y., Liu, T.-Y., Hewelett, H. L., and Moss, J., 1985, ADP-ribosylation of transducin by pertussis toxin, J. Biol. Chem., 260:13478.
Wheeler, G. L. and Bitensky, M. W., 1977, A light-activated GTPase in vertebrate photoreceptors: regulation of light-activated cyclic GMP phosphodiesterase, Proc. Natl. Acad. Sci., 74:4238.
Witt, P. L., Hamm, H. E., and Bownds, M.D., 1984, Preparation and characterization of monoclonal antibodies to several frog rod outer segment proteins, J. Gen. Physiol., 84:251.
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© 1990 Plenum Press, New York
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Mazzoni, M.R., Hamm, H.E. (1990). Physical Studies of α-βγ Subunit Interactions of the Rod Outer Segment G Protein, G t : Effects of Monoclonal Antibody Binding. In: Borsellino, A., Cervetto, L., Torre, V. (eds) Sensory Transduction. NATO ASI Series, vol 194. Springer, Boston, MA. https://doi.org/10.1007/978-1-4684-5841-1_11
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DOI: https://doi.org/10.1007/978-1-4684-5841-1_11
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