Ca2+ Release Channel

PKD2, also called polycystin 2, is a TRP-related protein defective in human autosomal polycystic kidney disease, the most common life-threatening genetic disease. PKD2 appears to be a cation channel in the plasma membrane, although there is evidence that it is an intracellular Ca2+release channel. Mammalian homologs include polycystin-like (PCL). 

Ryanodine receptor (RyR) is an intracellular Ca2+ release channel in the sarcoplasmic reticulum (SR) or the endoplasmic reticulum (ER). RyR binds ryanodine (a plant alkaloid, see Drugs) with a high affinity, after which it is named. 

Sarcoplasmic reticulum (SR) is a form of the smoothfaced endoplasmic reticulum (ER) in muscles. It functions as an intracellular Ca2+ store for muscle contraction. Ca2+ is energetically sequestered into the SR by Ca2+-pump/sarcoplasmic endoplasmic reticulum Ca2+-ATPase (SERCA) and released via Ca2+ release channels on stimuli (ryanodine receptor in striated muscles and inositol 1,4,5-trisphosphate receptor in most smooth muscles). Endoplasmic reticulum in non-muscle tissues also functions as an intracellular Ca2+ store. 

Campbell, K. P., Knudson, C. M., Imagawa, T. et al. Identification and characterization of the high affinity [1 3H]ryanodine receptor of the junctional sarcoplasmic reticulum Ca2+ release channel. /. Biol. Chem. 262 6460-6463,1987. 

Randriamampita C, Tsien RY 1993 Emptying of intracellular Ca2+ stores releases a novel small messenger that stimulates Ca2+ influx. Nature 364 809-814 Sutko JL, Airey JA 1996 Ryanodine receptor Ca2+ release channels does diversity in form equal diversity in function Physiol Rev 76 1027-1071... 

Neylon CB, Richards SM, Larsen MA, Agrotis A, Bobik A 1995 Multiple types of ryanodine receptor/Ca2+ release channels are expressed in vascular smooth muscle. Biochem Biophys Res Commun 215 814—821... 

An initial hint that Ca2+ stores are present and functional in smooth muscle cells came from earlier experiments revealing that agonist-induced contractions could be observed in the absence of extracellular Ca2+. It is now known that smooth muscle Ca2+ stores express two types of Ca2+ release channels, the ryanodine receptor (RyR) and the inositol-1,4,5-trisphosphate (L1SP3) receptor (L1SP3R) (Somlyo Somlyo 1994). Recent studies have shown that Ca2+ release from intracellular Ca2+ stores plays various important roles in the regulation of smooth muscle contraction. Local and transient releases of Ca2+ from RyR near the surface membrane, which are called Ca2+ sparks, activate Ca2+-sensitive K+... 

Our studies of the structures giving rise to sparks suggest that the SR is the source of Ca2+ release through ryanodine receptors which act as Ca2+ release channels, but that adjacent InsP3 receptors can influence the behaviour of the... 

Arnaudeau S, Macrez-Lepretre N, Mironneau J 1996 Activation of calcium sparks by angiotensin II in vascular myocytes. Biochem Biophys Res Commun 222 809-815 Arnaudeau S, Boittin FX, Macrez N, Lavie JL, Mironneau C, Mironneau J 1997 L-type and Ca2+ release channel-dependent hierarchical Ca2+ signalling in rat portal vein myocytes. Cell... 

Benham CD, Bolton TB 1986 Spontaneous transient outward currents in single visceral and vascular smooth muscle cells of the rabbit. J Physiol 381 385—406 Boittin FX, Coussin F, Macrez N, Mironneau C, Mironneau J 1998 Inositol 1,4,5-trisphosphate-and ryanodine-sensitive Ca2+ release channel-dependent Ca2+ signalling in rat portal vein... 

In smooth muscle, the sarcoplasmic reticulum (SR) plays an important role in regulating cell excitability by communicating intimately with ion channels in the surface membrane. In most cases, Ca2+ release from ryanodine-sensitive Ca2+ release channels (RyRs) in the SR leads to a paradoxical decrease in smooth muscle cell excitability due to activation of plasma membrane K+ channels (Fig. 1 Nelson et al 1995). This is in stark contrast to cardiac muscle, where Ca2+ release from RyRs supplies the majority (> 90%) of Ca2+ required for contraction (Cheng et al 1993, Cannell et al 1995). In this paper, we will briefly review the basic... 

Rousseau E, Smith JS, Meissner G 1987 Ryanodine modifies conductance and gating behavior of single Ca2+ release channel. Am J Physiol 253 C364—C368 Wallner M, Meera P, Toro L 1999 Molecular basis of fast inactivation in voltage and Ca2+-activated K+ channels a transmembrane /) subunit homolog. Proc Natl Acad Sci USA 96 4137-4142... 

Kuemmerle JF, Murthy KS, Makhlouf GM 1994 Agonist-activated, ryanodine-sensitive, IP3-insensitive Ca2+ release channels in longitudinal muscle of intestine. Am J Physiol 266 C1421-C1431... 

Kotlikoff I have a question about InsP3 receptors and ryanodine receptors. There is good evidence for wave propagation with both systems in smooth muscle. Can you say anything in experiments where you have looked with antibodies about the relationship between InsP3 receptors and ryanodine receptors And does this provide any insight into the interaction between these Ca2+-sensitive intracellular Ca2+ release channels ... 

Ankyrins are intracellular proteins that associate with a variety of transport proteins including Na+ channels, Na +, K+ ATPase, Na +, Ca2+ exchange, Ca2+ release channels. 

Diagram of the structures involved in the stretch reflex arc. I is an inhibitory interneuron E indicates an excitatory presynaptic terminal la is a primary intrafusal afferent fiber Ca2+ denotes activator calcium stored in the sarcoplasmic reticulum of skeletal muscle RyR channels indicates the Ca2+ release channels. 

Blocks RyRl Ca2+-release channels in the sarcoplasmic reticulum of skeletal muscle... 

There have been three reports of the same dimeric disulfide. It was first isolated from an unidentified sponge from Guam and the structure elucidated by analysis of spectral data. The (E,E) stereochemistry of the disulfide (500) was defined by comparing the I3C NMR spectroscopic data with those of the (E,Z)-isomer (501) that was obtained as an unstable minor product [425]. Compound 500 was isolated from a species of Psammaplysilla and was called psammaplin A [426]. It was also isolated from Thorectopsamma xana, collected from the same location in Guam, together with a minor dimeric metabolite bisaprasin (502). Both compounds inhibited growth of Staphylococcus aureus and Bacillus subtilis [427]. Psammaplin A (bisprasin) (500) was later isolated from a Dysidea species of sponge and shown to act on Ca2+-induced Ca2+ release channels of skeletal muscle [428]. 

The problem, both in pigs and in humans susceptible to malignant hyperthermia, was found in the Ca2+ release channels (ryanodine receptors). Study of inheritance in human families together... 

Treves S, Scutari E, Robert M, Groh S, Ottolia M, Prestipino G, Ronjat M, Zorzato F. 1997. Interaction of S100A1 with the Ca2+ release channel (ryanodine receptor) of skeletal muscle. Biochemistry 36(38) 11496-11503. 

Meissner G (1994) Ryanodine receptor/Ca2+ release channels and their regulation by endogenous effectors. Annu Rev Physiol 56 485-508. 

Abstract Mutations in two intracellular Ca2+ release channels or ryanodine receptors (RyRl... 

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