Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:4.6.1.2 (guanylate cyclase)
8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recoverin (Rv) is a myristoylated Ca(2+)-binding protein present primarily in bovine photoreceptors. It represents a newly identified family of neuronal specific Ca(2+)-binding proteins that includes neurocalcin, hippocalcin, and guanylyl cyclase-activating protein. To investigate the function of Rv in photoreceptors, we identified proteins that bind immobilized Rv in a Ca(2+)-dependent manner. Rhodopsin kinase (RK), interphotoreceptor retinoid-binding protein, and tubulin interact with Rv in the presence of Ca2+. The importance of the Rv/RK interaction was further characterized. RK, purified using immobilized Rv as an affinity matrix, catalyzed the light-dependent and Ca(2+)-independent incorporation of phosphates into rhodopsin when reconstituted with urea-stripped rod outer segment membranes. When only a small fraction (0.04%) of rhodopsin was photolyzed, as many as 700 phosphates were incorporated per photolyzed rhodopsin, a phenomenon known as "high gain" phosphorylation. When recoverin was added, the activity of RK became sensitive to free Ca2+, with EC50 = 3 microM. The N-terminal myristoyl residue of Rv enhances the inhibitory effect of Rv and introduces cooperativity to the Ca(2+)-dependent inhibition of rhodopsin phosphorylation. Rv neither interacts with other members of the G-protein-coupled receptor kinase family such as beta-adrenergic receptor kinase 1 nor inhibits beta-adrenergic receptor kinase 1 activity. The specific and Ca(2+)-dependent Rv/RK interaction is necessary for the inhibitory effect of Rv on rhodopsin phosphorylation and may play an important role in photoreceptor light adaptation.
...
PMID:Ca(2+)-dependent interaction of recoverin with rhodopsin kinase. 762 15

Photobleaching of rhodopsin in rod photoreceptors activates the visual cascade system leading to a decrease in cyclic GMP and the closure of cGMP-gated channels in the rod outer segment plasma membrane. Calcium plays an important role in the recovery of the rod outer segment to its dark state by regulating the resynthesis of cGMP by guanylate cyclase. Here we report that calmodulin, a Ca(2+)-binding protein present in the rod outer segment, increases the apparent Michaelis constant of the channel for cGMP. This results in a decrease in the rate of cation influx into the rod outer segment by two- to sixfold at low cGMP concentrations and has the effect of increasing the sensitivity of the channel to small changes in cGMP levels during phototransduction. Biochemical studies indicate that calcium-calmodulin binds to a protein of M(r) 240K which is tightly associated with the channel. On the basis of these studies, Ca2+ is suggested to play a central role in photorecovery and light adaptation, not only by regulating guanylate cyclase, possibly through recoverin, but also by modulating the cGMP-gated channel through calmodulin interaction with the 240K protein.
...
PMID:Modulation of the cGMP-gated channel of rod photoreceptor cells by calmodulin. 767 44

The bovine retina rod cell protein with an apparent M(r) 26 kDa (p26 [1] or recoverin [2]) was suggested to be a calcium-sensitive regulator of photoreceptor guanylate cyclase. The data obtained show that highly purified p26 is not capable of restoring guanylate cyclase in washed ROS membranes up to the level of a ROS suspension. At the same time we found that a Ca(2+)-sensitive complex of p26 and a protein with apparent M(r) 67 kDa, presumably rhodopsin kinase, is present in the ROS extract. We suggest that rhodopsin kinase can be a functional target for p26 in retina rod cells.
...
PMID:[Function of the calcium-binding protein p26 (recoverin) in bovine retinal rods]. 791 52

The calcium-dependent modulation of type A K+ current (IA) has been investigated using a two-electrode voltage clamp on larval muscle cells of Drosophila. It was found that the amplitude of IA increases when [Ca2+]o is changed from 0.2 mM to 2 mM. The increase in IA amplitude is not due to overlap with the Ca(2+)-dependent fast K+ current, ICF, since it is observed also in slo1 mutants, which are deficient for this current. This effect is not due to Ca(2+)-dependent shifts in the steady-state activation/inactivation kinetics. The phenomenon is probably due to elevations in internal calcium since it is abolished by Ca2+ channel blockers and promoted by caffeine (5 mM) if added in the absence of external calcium. This calcium effect was dose-dependent since it was not observed in the presence caffeine plus 2 mM calcium in the bath nor for values of [Ca2+]o above 4 mM. The Ca(2+)-dependent modulation of IA is absent in V7, a mutation that causes overexpression of frequenin, a recoverin-like Ca(2+)-binding protein which stimulates guanylyl cyclase [31]. One possible explanation for the loss of IA modulation in the V7 mutation is that the excess of frequenin alters intracellular cGMP-dependent metabolic pathways responsible for the internal calcium homeostasis.
...
PMID:Modulation of type A K+ current in Drosophila larval muscle by internal Ca2+; effects of the overexpression of frequenin. 805 77

The T(X;Y)V7 rearrangement in Drosophila has originally been recognized as a Shaker-like mutant because of its behavioral and electrophysiological phenotype. The gene whose expression is altered by the V7 rearrangement has been characterized. It encodes a novel Ca(2+)-binding protein named frequenin, which is related to recoverin and visinin. In vitro, the frequenin protein functions like recoverin as a Ca(2+)-sensitive guanylyl cyclase activator. Anti-frequenin antibodies stain the central and peripheral nervous system in Drosophila embryos and in larval and adult tissue sections. Frequenin appears to be particularly enriched in synapses, such as the motor nerve endings at neuromuscular junctions. Neuromuscular junctions of transgenic flies, which overexpress frequenin upon heat shock, exhibit an extraordinarily enhanced, frequency-dependent facilitation of neurotransmitter release, with properties identical to those observed in V7 junctions. We propose that frequenin represents a new element for the Ca(2+)-dependent modulation of synaptic efficacy.
...
PMID:Frequenin--a novel calcium-binding protein that modulates synaptic efficacy in the Drosophila nervous system. 810 11

We purified and sequenced from bovine brain a novel calcium-binding protein. This protein which we named neurocalcin has 3 putative EF hand motifs and a close homology with recoverin which activates guanylate cyclase Ca2+ dependently. Neurocalcin has at least 6 isoforms and is expressed in the central nervous system (CNS), retina and adrenal gland. Considering unique distribution of neurocalcin, this protein may an important physiological role which differs from that of visinin or recoverin.
...
PMID:Neurocalcin family: a novel calcium-binding protein abundant in bovine central nervous system. 838 72

In vertebrate photoreceptors, light induces hydrolysis of cGMP by activating cGMP phosphodiesterase (PDE), which results in closure of the cGMP-activated cation channel. During light adaptation, the cytoplasmic Ca2+ concentration decreases, and this decrease is one of the underlying mechanisms of light adaptation. Sensitivity-modulating protein (S-modulin) is a Ca(2+)-binding protein involved in light adaptation in frog rods; it regulates both the light sensitivity of PDE and the lifetime of activated PDE by controlling rhodopsin phosphorylation in a Ca(2+)-dependent manner. Recoverin has been reported as a Ca(2+)-dependent regulator of guanylate cyclase in bovine rods (Dizhoor, A. M., Ray, S., Kumar, S., Niemi, G., Spencer, M., Brolley, D., Walsh, K. A. Philipov, P. P., Hurley, J. B., and Stryer, L. (1991) Science 251, 915-918). Here, we show that recoverin has similar activity as S-modulin, and the amino acid sequences of both proteins are similar. The results strongly suggest that recoverin is bovine S-modulin and regulates PDE activation.
...
PMID:Recoverin has S-modulin activity in frog rods. 839 55

A 23-kDa, soluble, calcium-binding photoreceptor-specific protein (23-kDa) has been shown to be identical to recoverin and the cancer-associated retinopathy protein. Recoverin has been reported to activate guanylate cyclase to increase the amount of cyclic GMP and thereby reopen cation channels within the photoreceptor cells. In this study, the 23-kDa protein was purified from bovine retinas and monospecific antibodies against it were generated in rabbits. Western analysis demonstrated 23-kDa in retinas from human, monkey, bovine, dog, rabbit, rat, mouse, frog, chameleon and iguana although it was not detected in chicken or fly retinas. No immunoreactivity was observed in any non-retinal tissues except the pineal gland. The 23-kDa protein was detected, by Western analysis, at postnatal day 5 in the mouse retina and it increased in amount in parallel with the differentiation of the photoreceptor cells in normal mice and it also decreased in parallel with their degeneration in the rd mouse. Immunocytochemical analysis of the adult mouse retina showed that 23-kDa is restricted primarily to the inner segments of the photoreceptor cells and, unlike arrestin, its localization did not shift in response to light/dark changes.
...
PMID:Developmental appearance, species and tissue specificity of mouse 23-kDa, a retinal calcium-binding protein (recoverin). 840 85

The rod photoresponse is triggered by an enzyme cascade that stimulates cGMP hydrolysis. The resulting fall in cGMP leads to a decrease in Ca2+, which promotes photoresponse recovery by activating guanylate cyclase, causing cGMP resynthesis. In vitro biochemical studies suggest that Ca2+ activation of guanylate cyclase is medicated by recoverin, a 26 kd Ca(2+)-binding protein. To evaluate this, exogenous bovine recoverin and two other homologous Ca(2+)-binding proteins from chicken and Gecko retina were dialyzed into functionally intact Gecko rods using whole-cell recording. All three proteins prolonged the rising phase of the photoresponse without affecting the kinetics of response recovery. These results suggest that recoverin-like proteins affect termination of the transduction cascade, rather than mediate Ca(2+)-sensitive activation of guanylate cyclase.
...
PMID:The effect of recoverin-like calcium-binding proteins on the photoresponse of retinal rods. 846 Nov 39

In the process of photoreceptor signal transduction, light initiates an enzymatic cascade that leads to hydrolysis of cyclic GMP (cGMP) and closure of cGMP-gated sodium-calcium channels resulting in photoreceptor hyperpolarization. Recoverin is a calcium-binding protein that is thought to reverse the effects of light on cGMP levels by activating guanylate cyclase. Guanylate cyclase produces cGMP to overcome the cGMP-hydrolysing effect of phosphodiesterase, and reopens the sodium-calcium channels in photoreceptor outer segments. We have cloned and sequenced a cDNA encoding recoverin in human retina. The human nucleotide sequence is 88% identical to the bovine sequence, and contains a 600-base pair (bp) open reading frame encoding 200 amino acids. In situ hybridization of cultured Y79 human retinoblastoma cells with a radioactive recoverin cDNA probe showed intense, specific labeling of the cytoplasm, indicating the presence of mRNA encoding recoverin. Direct sequencing of a Y79 retinoblastoma cDNA polymerase chain reaction (PCR) product confirmed the presence of recoverin in this human cell line.
...
PMID:Molecular cloning and nucleotide sequence of a cDNA encoding recoverin from human retina. 850 May 58


<< Previous 1 2 3 4 5 6 Next >>

---