Ca2+-binding proteins in the retina: Structure, function, and the etiology of human visual diseases

Abstract

The complex sensation of vision begins with the relatively simple photoisomerization of the visual pigment chromophore 11‐cis‐retinal to its all‐trans configuration. This event initiates a series of biochemical reactions that are collectively referred to as phototransduction, which ultimately lead to a change in the electrochemical signaling of the photoreceptor cell. To operate in a wide range of light intensities, however, the phototransduction pathway must allow for adjustments to background light. These take place through physiological adaptation processes that rely primarily on Ca2+ ions. While Ca2+ may modulate some activities directly, it is more often the case that Ca2+‐binding proteins mediate between transient changes in the concentration of Ca2+ and the adaptation processes that are associated with phototransduction. Recently, combined genetic, physiological, and biochemical analyses have yielded new insights about the properties and functions of many phototransduction‐specific components, including some novel Ca2+‐binding proteins. Understanding these Ca2+‐binding proteins will provide a more complete picture of visual transduction, including the mechanisms associated with adaptation, and of related degenerative diseases. BioEssays 22:337–350, 2000. © 2000 John Wiley & Sons, Inc.

Synaptic transmission at retinal ribbon synapses

“…A Na/Ca, K exchanger (Schnetkamp et al, 1989) (Palczewski et al, 2000). However, outer and inner segment mechanisms for Ca 2+ homeostasis are different and substantially independent (reviewed in Krizaj and Copenhagen, 2002).…”

Calcium-sensitive Regions of GCAP1 as Observed by Chemical Modifications, Fluorescence, and EPR Spectroscopies

“…In recent years an interesting group of neuronal calciumbinding proteins (NCBP) 1 (1, 2) (also known as neuronal calcium sensors (3)) was discovered and characterized to varying degrees. Better known members of this family include recoverin (4 -10), hippocalcin (11)(12)(13), neurocalcin (14 -17), frequenin (18 -22), visinin (23,24), guanylyl cyclase-activating proteins (GCAPs) 1-3 (2,25), and guanylyl cyclase-inhibitory protein (26). NCBPs are 19 -25-kDa proteins with four EFhand motifs and are slightly larger than CaM (ϳ17 kDa).…”

G Protein-Coupled Receptor Rhodopsin: A Prospectus

“…As with any rich subject, not all of the nuances of rhodopsin structure and function can be covered here. Therefore, the authors encourage readers to peruse other reviews dedicated to rhodopsin and different aspects of phototransduction (6,21,(29)(30)(31)(32)(33)(34)(35)(36).…”