Cyclic nucleotide gated channel beta 1, also known as CNGB1, is a human gene encoding an ion channel protein. [3]
Cyclic nucleotide gated channel beta 1, also known as CNGB1, is a human gene encoding an ion channel protein. [3]
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 in rods. Rhodopsin mediates dim light vision and thus is extremely sensitive to light. When rhodopsin is exposed to light, it immediately photobleaches. In humans, it is regenerated fully in about 30 minutes, after which the rods are more sensitive. Defects in the rhodopsin gene cause eye diseases such as retinitis pigmentosa and congenital stationary night blindness.
Achromatopsia, also known as Rod monochromacy, is a medical syndrome that exhibits symptoms relating to five conditions, most notably monochromacy. Historically, the name referred to monochromacy in general, but now typically refers only to an autosomal recessive congenital color vision condition. The term is also used to describe cerebral achromatopsia, though monochromacy is usually the only common symptom. The conditions include: monochromatic color blindness, poor visual acuity, and day-blindness. The syndrome is also present in an incomplete form that exhibits milder symptoms, including residual color vision. Achromatopsia is estimated to affect 1 in 30,000 live births worldwide.
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 into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential.
Cyclic nucleotide–gated ion channels or CNG channels are ion channels that function in response to the binding of cyclic nucleotides. CNG channels are nonselective cation channels that are found in the membranes of various tissue and cell types, and are significant in sensory transduction as well as cellular development. Their function can be the result of a combination of the binding of cyclic nucleotides and either a depolarization or a hyperpolarization event. Initially discovered in the cells that make up the retina of the eye, CNG channels have been found in many different cell types across both the animal and the plant kingdoms. CNG channels have a very complex structure with various subunits and domains that play a critical role in their function. CNG channels are significant in the function of various sensory pathways including vision and olfaction, as well as in other key cellular functions such as hormone release and chemotaxis. CNG channels have also been found to exist in prokaryotes, including many spirochaeta, though their precise role in bacterial physiology remains unknown.
X-linked retinitis pigmentosa GTPase regulator is a GTPase-binding protein that in humans is encoded by the RPGR gene. The gene is located on the X-chromosome and is commonly associated with X-linked retinitis pigmentosa (XLRP). In photoreceptor cells, RPGR is localized in the connecting cilium which connects the protein-synthesizing inner segment to the photosensitive outer segment and is involved in the modulation of cargo trafficked between the two segments.
ATP-binding cassette, sub-family A (ABC1), member 4, also known as ABCA4 or ABCR, is a protein which in humans is encoded by the ABCA4 gene.
Peripherin-2 is a protein, that in humans is encoded by the PRPH2 gene. Peripherin-2 is found in the rod and cone cells of the retina of the eye. Defects in this protein result in one form of retinitis pigmentosa, an incurable blindness.
Rod cGMP-specific 3',5'-cyclic phosphodiesterase subunit beta is the beta subunit of the protein complex PDE6 that is encoded by the PDE6B gene. PDE6 is crucial in transmission and amplification of visual signal. The existence of this beta subunit is essential for normal PDE6 functioning. Mutations in this subunit are responsible for retinal degeneration such as retinitis pigmentosa or congenital stationary night blindness.
Cyclic nucleotide-gated cation channel alpha-3 is a protein that in humans is encoded by the CNGA3 gene.
Guanine nucleotide-binding protein G(t) subunit alpha-2 is a protein that in humans is encoded by the GNAT2 gene.
Retinal rod rhodopsin-sensitive cGMP 3',5'-cyclic phosphodiesterase subunit gamma is an enzyme that in humans is encoded by the PDE6G gene.
Guanine nucleotide-binding protein G(t) subunit alpha-1 is a protein that in humans is encoded by the GNAT1 gene.
Cyclic nucleotide gated channel beta 3, also known as CNGB3, is a human gene encoding an ion channel protein.
Cyclic nucleotide-gated channel alpha 1, also known as CNGA1, is a human gene encoding an ion channel protein. Heterologously expressed CNGA1 can form a functional channel that is permeable to calcium. In rod photoreceptors, however, CNGA1 forms a heterotetramer with CNGB1 in a 3:1 ratio. The addition of the CNGB1 channel imparts altered properties including more rapid channel kinetics and greater cAMP-activated current. When light hits rod photoreceptors, cGMP concentrations decrease causing rapid closure of CNGA1/B1 channels and, therefore, hyperpolarization of the membrane potential.
Rod outer segment membrane protein 1 is a protein that in humans is encoded by the ROM1 gene.
Retinal rod rhodopsin-sensitive cGMP 3',5'-cyclic phosphodiesterase subunit delta is an enzyme that in humans is encoded by the PDE6D gene. PDE6D was originally identified as a fourth subunit of rod cell-specific cGMP phosphodiesterase (PDE). The precise function of PDE delta subunit in the rod specific GMP-PDE complex is unclear. In addition, PDE delta subunit is not confined to photoreceptor cells but is widely distributed in different tissues. PDE delta subunit is thought to be a specific soluble transport factor for certain prenylated proteins and Arl2-GTP a regulator of PDE-mediated transport.
Rod cGMP-specific 3',5'-cyclic phosphodiesterase subunit alpha is an enzyme that in humans is encoded by the PDE6A gene.
Cyclic nucleotide gated channel alpha 2, also known as CNGA2, is a human gene encoding an ion channel protein.
Cyclic nucleotide-gated cation channel alpha-4 is a protein that in humans is encoded by the CNGA4 gene.
Proteins that bind cyclic nucleotides share a structural domain of about 120 residues. The best studied of these proteins is the prokaryotic catabolite gene activator where such a domain is known to be composed of three alpha-helices and a distinctive eight-stranded, antiparallel beta-barrel structure. There are six invariant amino acids in this domain, three of which are glycine residues that are thought to be essential for maintenance of the structural integrity of the beta-barrel. cAMP- and cGMP-dependent protein kinases contain two tandem copies of the cyclic nucleotide-binding domain. The cAPK's are composed of two different subunits, a catalytic chain and a regulatory chain, which contains both copies of the domain. The cGPK's are single chain enzymes that include the two copies of the domain in their N-terminal section. Vertebrate cyclic nucleotide-gated ion-channels also contain this domain. Two such cations channels have been fully characterized, one is found in rod cells where it plays a role in visual signal transduction.
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