Abstract
Photolyzed rhodopsin was phosphorylated in bovine rod outer segments incubated at −10‡ C. In the experiment in which urea-treated outer segments and rhodopsin kinase were incubated with ATP in the presence of 30% glycerol, the extent of phosphate incorporation at −10‡ C was about 30% of that at 37‡ C. Separation of phosphorylated rhodopsin by isoelectric focusing indicated that a limited number of sites were phosphorylated at −10‡ C. The partially phosphorylated pigment incorporated more phosphates when the temperatures was raised to 37‡ C. This was partly due to decreased inhibition of phosphorylation by glycerol at higher temperature. Since the maximum phosphorylation at −10‡ C (at which metarhodopsin II is stable) occurred at a pH value (6.0) lower than the pKa for metarhodopsin I-metarhodopsin II transition, metarhodopsin II was suggested to be the preferred substrate for rhodopsin kinase at −10‡ C. Limited proteolysis with thermolysin of rhodopsin phosphorylated at 37‡ C released peptides containing about 50% of the total phosphate incorporated. In contrast, proteolytic digestion of rhodopsin phosphorylated at −10‡ C released negligible amounts of phosphate-containing peptides. The results were taken to suggest that the incorporation of phosphates at metarhodopsin II level under the present condition occurred in the residues other than those removed by thermolysin digestion.
Similar content being viewed by others
References
Aton GB, Litman BL (1982) Phosphorylation sites on rhodopsin. ARVO (Assoc Res Vision Ophthalmol) Abstract, p 229
Fukuda Y, Kawamura S, Yoshizawa T, Miki N (1981) Activation of phosphodiesterase in frog outer segment by an intermediate of rhodopsin photolysis I. Biochim Biophys Acta 675: 188–194
Fung BK-K, Hurley JB, Stryer L (1981) Flow of information in the light-triggered cyclic nucleotide cascade of vision. Proc Natl Acad Sci USA 78: 152–156
Hargrave PA, Fong S-L (1977) The amino- and carboxyl-terminal sequence of bovine rhodopsin. J Supramol Struct 6: 559–570
Kühn H, McDowell JH (1977) Isoelectric focusing of phosphorylated cattle rhodopsin. Biophys Struct Mech 3: 199–203
Liebman PA (1981) Control of cyclic GMP phosphodiesterase in visual relevance to hormone receptor mechanisms. In: Sears ML (ed) New directions in ophthalmic research. Yale University Press, New Haven London, pp 207–222
Liebman PA, Pugh EN (1980) ATP mediated rapid reversal of cyclic GMP phosphodiesterase activation in visual receptor membranes. Nature (London) 287: 734–736
Matthews RG, Hubbard R, Brown PK, Wald G (1963) Tautomeric forms of metarhodopsin. J Gen Physiol 47: 215–240
Miki N, Keirns JJ, Marcus FR, Freeman J, Bitensky MW (1973) Regulation of cyclic nucleotide concentrations in photoreceptors: An ATP-dependent stimulation of cyclic nucleotide phosphodiesterase by light. Proc Natl Acad Sci USA 76: 3820–3824
Pober JS, Stryer L (1975) Light dissociates enzymatically-cleaved rhodopsin into different fragments. J Mol Biol 95: 477–481
Shichi H (1981) Guanosine nucleotide metabolism in the bovine rod outer segment: Distribution of enzymes and a role of GTP. In: Miller WH (ed) Molecular mechanism of photoreceptor transduction. Academic Press, New York. (Current topics in membranes and transport, pp 273–289)
Shichi H, Somers RL (1980) Distribution of enzymes involved in nucleotide metabolism in the disk and other rod membranes. Photochem Photobiol 32: 491–495
Shichi H, Somers RL (1978) Light-dependent phosphorylation of rhodopsin. J Biol Chem 253: 7040–7046
Wilden U, Kühn, H (1982) Light-dependent phosphorylation of rhodopsin: Number of phosphorylation sites. Biochemistry 21: 3014–3022
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yamamoto, K., Shichi, H. Rhodopsin phosphorylation occurs at metarhodopsin II level. Biophys. Struct. Mechanism 9, 259–267 (1983). https://doi.org/10.1007/BF00535661
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00535661