The application outlines studies to examine the molecular basis of visual signalling in cone photoreceptors of the mammalian retina. Cones signal using a cGMP cascade pathway similar to that of rod photoreceptors; they differ from rods in their sensitivity, rate and amplitude of signaling, and adaptation properties. In lieu of biochemical methods, the identity of the components will be established through molecular cloning; their functional properties will be examined following in vitro expression. In previous research periods, we have identified and characterized the cDNAs and genes encoding the components of visual signaling in rods.
Our specific aims i n this term are to use the set of rod genes as probes to identify and characterize the homologous components that contribute to signaling in the red/green cones and blue cones. Potential candidates for cone cDNAs will be identified through the technique of homology cloning. Their specific cone-type identity will be determined by in situ hybridization studies. To examine the structure and function of cone signaling proteins, the components will be expressed in eucaryotic host cells. Comparative functional studies for rod, red/green cone and blue cone components will be carried out for the opsins by examination of the bleaching profile and activation of G-proteins. The differences in functioning of cGMP phosphodiesterases in rod and cones will be studied in systems reconstituted with opsins and G-proteins. The potential differences in rod and cone cGMP-dependent channels and Na+/Ca2+ exchangers will be examined biochemically in lipid vesicle flux assays. We seek to provide basic information about our most intensively used and least understood photoreceptors. The identification of genes expressed in cone cell types and the characterization of their gene products is a first step towards defining how cones function. The studies will provide tools to investigate the underlying basis of macular degeneration and retinal degenerations that affect cone cells. The characterization of gene structure will enable ourselves and other investigators to undertake studies of the molecular basis of development of rods and cones and ultimately to understand defects in development.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Visual Sciences A Study Section (VISA)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Chicago
Schools of Medicine
United States
Zip Code
Applebury, M L; Farhangfar, F; Glosmann, M et al. (2007) Transient expression of thyroid hormone nuclear receptor TRbeta2 sets S opsin patterning during cone photoreceptor genesis. Dev Dyn 236:1203-12
Fasick, Jeffry I; Applebury, Meredithe L; Oprian, Daniel D (2002) Spectral tuning in the mammalian short-wavelength sensitive cone pigments. Biochemistry 41:6860-5
Applebury, M L; Antoch, M P; Baxter, L C et al. (2000) The murine cone photoreceptor: a single cone type expresses both S and M opsins with retinal spatial patterning. Neuron 27:513-23
Wilson, C J; Copeland, R A (1997) Spectroscopic characterization of arrestin interactions with competitive ligands: study of heparin and phytic acid binding. J Protein Chem 16:755-63
Wagner, E; McCaffery, P; Mey, J et al. (1997) Retinoic aid increases arrestin mRNA levels in the mouse retina. FASEB J 11:271-5
Aparicio, J G; Applebury, M L (1995) The bovine photoreceptor outer segment guanylate cyclase: purification, kinetic properties, and molecular size. Protein Expr Purif 6:501-11
Wood, R L; Park, K H; Gierow, J P et al. (1994) Immunogold localization of prolactin in acinar cells of lacrimal gland. Adv Exp Med Biol 350:75-7
Pierce, M E; Sheshberadaran, H; Zhang, Z et al. (1993) Circadian regulation of iodopsin gene expression in embryonic photoreceptors in retinal cell culture. Neuron 10:579-84
Lem, J; Applebury, M L; Falk, J D et al. (1991) Tissue-specific and developmental regulation of rod opsin chimeric genes in transgenic mice. Neuron 6:201-10
Leser, G P; Nicoll, D A; Applebury, M L (1991) Distinctive properties of the purified Na-Ca exchanger from rod outer segments. Ann N Y Acad Sci 639:222-33

Showing the most recent 10 out of 21 publications