Recoverin (abbreviated Recov) is a 23 kilodalton (kDa) neuronal calcium-binding protein that is primarily detected in the

photoreceptor cell A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiatio ...

s of the eye. It plays a key role in the inhibition of

rhodopsin kinase Rhodopsin kinase (, ''rod opsin kinase'', ''G-protein-coupled receptor kinase 1'', ''GPCR kinase 1'', ''GRK1'', ''opsin kinase'', ''opsin kinase (phosphorylating)'', ''rhodopsin kinase (phosphorylating)'', ''RK'', ''STK14'') is a serine/threonine-s ...

, a molecule which regulates the

phosphorylation In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, wh ...

rhodopsin Rhodopsin, also known as visual purple, is a protein encoded by the RHO gene and a G-protein-coupled receptor (GPCR). It is the opsin of the rod cells in the retina and a light-sensitive receptor protein that triggers visual phototransduction ...

. A reduction in this inhibition helps regulate

sensory adaptation Neural adaptation or sensory adaptation is a gradual decrease over time in the responsiveness of the sensory system to a constant stimulus. It is usually experienced as a change in the stimulus. For example, if a hand is rested on a table, the tabl ...

in the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

, since the light-dependent channel closure in photoreceptors causes calcium levels to decrease, which relieves the inhibition of

by calcium-bound recoverin, leading to a more rapid inactivation of metarhodopsin II (activated form of rhodopsin).

Structure & Function

Recoverin is involved in the recovery phase of visual excitation and in adaptation to background light. It controls the life span of photoexcited rhodopsin by helping to inhibit

. An image of bovine recoverin with 3.00 Å resolution is shown.; This three-dimensional structure was determined by X-ray diffraction. Covalently attached at the amino-terminal of recoverin is a myristoyl group. When the protein binds calcium ions, it undergoes a conformational change and brings out the myristoyl group from the binding portion so that the group is able to either interact with the target or the protein can move to a different region. When recoverin is not bound to calcium, it stays in cytosol. When recoverin binds calcium, it migrates to the disc membrane and is embedded into the membrane using the myristoyl group to anchor itself. This calcium-bound form of recoverin slows the activity of

, resulting in the prolongation of light sensitivity for rhodopsin. Recent publications point out additional functions for recoverin. For instance, it goes through a light-dependent intracellular translocation to rod synaptic terminals and improves the signal transfer between rods and rod bipolar cells in the retina of mice. In humans, the recoverin protein is encoded by the ''RCVRN''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

References

External links

* {{Eye proteins EF-hand-containing proteins