Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in peripheral vision. On average, there are approximately 92 million rod cells in the human retina. Rod cells are more sensitive than cone cells and are almost entirely responsible for night vision. However, rods have little role in color vision, which is the main reason why colors are much less apparent in dim light.
Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells in the vertebrate retina. A photon is absorbed by a retinal chromophore, which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve.
Lipid signaling, broadly defined, refers to any biological cell signaling event involving a lipid messenger that binds a protein target, such as a receptor, kinase or phosphatase, which in turn mediate the effects of these lipids on specific cellular responses. Lipid signaling is thought to be qualitatively different from other classical signaling paradigms because lipids can freely diffuse through membranes. One consequence of this is that lipid messengers cannot be stored in vesicles prior to release and so are often biosynthesized "on demand" at their intended site of action. As such, many lipid signaling molecules cannot circulate freely in solution but, rather, exist bound to special carrier proteins in serum.
Hippocalcin is a protein that in humans is encoded by the HPCA gene.
G protein-coupled receptor kinases are a family of protein kinases within the AGC group of kinases. Like all AGC kinases, GRKs use ATP to add phosphate to Serine and Threonine residues in specific locations of target proteins. In particular, GRKs phosphorylate intracellular domains of G protein-coupled receptors (GPCRs). GRKs function in tandem with arrestin proteins to regulate the sensitivity of GPCRs for stimulating downstream heterotrimeric G protein and G protein-independent signaling pathways.
Cortactin is a monomeric protein located in the cytoplasm of cells that can be activated by external stimuli to promote polymerization and rearrangement of the actin cytoskeleton, especially the actin cortex around the cellular periphery. It is present in all cell types. When activated, it will recruit Arp2/3 complex proteins to existing actin microfilaments, facilitating and stabilizing nucleation sites for actin branching. Cortactin is important in promoting lamellipodia formation, invadopodia formation, cell migration, and endocytosis.
Neurocalcin is a neuronal calcium-binding protein that belongs to the neuronal calcium sensor (NCS) family of proteins. It expressed in mammalian brains. It possesses a Ca2+/myristoyl switch
Neuronal calcium sensor-1 (NCS-1) also known as frequenin homolog (Drosophila) (freq) is a protein that is encoded by the FREQ gene in humans. NCS-1 is a member of the neuronal calcium sensor family, a class of EF hand containing calcium-myristoyl-switch proteins.
Rhodopsin kinase is a serine/threonine-specific protein kinase involved in phototransduction. This enzyme catalyses the following chemical reaction:
Mitogen-activated protein kinase 3, also known as p44MAPK and ERK1, is an enzyme that in humans is encoded by the MAPK3 gene.
Calcium/calmodulin-dependent protein kinase type IV is an enzyme that in humans is encoded by the CAMK4 gene.
Sodium-hydrogen exchange regulatory cofactor NHE-RF2 (NHERF-2) also known as tyrosine kinase activator protein 1 (TKA-1) or SRY-interacting protein 1 (SIP-1) is a protein that in humans is encoded by the SLC9A3R2 gene.
Glycylpeptide N-tetradecanoyltransferase 1 also known as myristoyl-CoA:protein N-myristoyltransferase 1 (NMT-1) is an enzyme that in humans is encoded by the NMT1 gene. It belongs to the protein N-terminal methyltransferase and glycylpeptide N-tetradecanoyltransferase family of enzymes.
Cyclin-dependent kinase 5 activator 1 is an enzyme that in humans is encoded by the CDK5R1 gene.
Calcium/calmodulin-dependent protein kinase type 1 is an enzyme that in humans is encoded by the CAMK1 gene.
S-arrestin is a protein that in humans is encoded by the SAG gene.
Phosducin, also known as PDC, is a human protein and gene. It belongs to the phosducin family of proteins.
Guanine nucleotide-binding protein G(T) subunit gamma-T1 is a protein that in humans is encoded by the GNGT1 gene. Either GNGT1 or GNGT2 is the gamma subunit (Gγ) of the Gβγ part of transducin, a heterotrimeric G-protein naturally expressed in vertebrate retina rod and cone cells. GNGT1 only occurs in rod cells, and GNGT2 only occurs in cone cells, with a different alpha (Gα) subunit.
Ras GTPase-activating protein 3 is an enzyme that in humans is encoded by the RASA3 gene.
G-protein-coupled receptor kinase 7 is a serine/threonine-specific protein kinase involved in phototransduction. This enzyme catalyses the phosphorylation of cone (color) photopsins in retinal cones during high acuity color vision primarily in the fovea.
