Store-operated Ca2+ channels

Pore-forming subunits of some forms of store-operated Ca2+ channels. 

Store-operated Ca2+ channels (593), of which CRACs (Ca2+-release activated channels) are the best characterized (594),... 

Xu S-Z, Beech D J 2001 TrpCl is a membrane-spanning subunit of store-operated Ca2+ channels in native vascular smooth muscle cells. Circ Res 88 84—87... 

Welsh DG, Morielli AD, Nelson MT, Brayden JE 2002 Transient receptor potential channels regulate myogenic tone of resistance arteries. Circ Res 90 248-250 Xu SZ, Beech DJ 2001 TrpCl is a membrane-spanning subunit of store-operated Ca2+ channels in native vascular smooth muscle cells. Circ Res 88 84-87 Yamazawa T, lino M, Endo M 1992 Presence of functionally different compartments of the Ca2+ store in single intestinal smooth muscle cells. FEBS Lett 301 181—184... 

Vanden Abeele, F., Lemonnier, L., Thebault, S., Lepage, G., Parys, J. B., Shuba, Y., Skryma, R. and Prevarskaya, N., 2004, Two types of store-operated Ca2+ channels with different activation modes and molecular origin in LNCaP human prostate cancer epithelial cells. J Biol Chem 279,... 

Kiselyov K, Mignery GA, Zhu MX, Muallem S 1999 The N-terminal domain of the IP3 receptor gates store-operated hTrp3 channels. Mol Cell 4 423-429 Lee HC 2000 NAADP An emerging calcium signaling molecule. J Membr Biol 173 1 -8 Lin S, Fagan KA, Li K-X, Shaul PW, Cooper DMF, Rodman DM 2000 Sustained endothelial nitric-oxide synthase activation requires capacitative Ca2+ entry. J Biol Chem 275 17979-17985... 

Gregory, R.B., Sykiotis, D., and Barritt, G.J. 2003. Evidence that store-operated Ca channels are more effective than intracellular messenger-activated non-selective cation channels in refilling rat hepatocyte intracellular Ca2+ stores. Cell Calcium 34, 241-251. 

G. Rocchitta, R. Migheli, M.P. Mura, G. Esposito, M.S. Desole, E. Miele, M. Miele, and P.A. Serra, Signalling pathways in the nitric oxide donor-induced dopamine release in the striatum of freely moving rats evidence that exogenous nitric oxide promotes Ca2+ entry through store-operated channels. Brain Res. 1023, 243-252 (2004). 

Channels associated with capacitative calcium ion entry have been characterized electrophysiologically. In leukocytes, the current associated with the depletion of intracellular Ca2+ stores is highly Ca2+-selective and, on the basis of noise analysis, is believed to involve minute single channels [16] (see Ch. 6). This is the calcium release-activated calcium current (ICrac)- In other cell types, currents with significantly different properties have been identified, including in some instances store-operated nonse-lective cation channels. These marked electrophysiological distinctions may be indicative of distinct channel types mediating capacitative calcium ion entry in different cell types. 

Kotlikoff Returning to the issue of receptor-operated or store-operated channels, one of the things I noticed in your traces was that your caffeine responses came back to baseline very smoothly. There was not the sustained elevation of [Ca2+] that you might predict. One of the things that is very different about voltage-clamped smooth muscle between a caffeine response and a phospholipase receptor-linked response is this additional current that is seen with the phospholipase receptor. I didn t see any functional evidence of a sustained response in your caffeine experiments. Have you voltage clamped these cells and looked to see whether there is any current there If not, do you think this is because the current is just too small to be able to measure ... 

McCarron No, although we only have indirect evidence for this. Our reasoning is that the tonic component is blocked by inhibitors of the voltage-dependent Ca2+ channel, and it is not blocked by the SKF96365 which blocks store-operated channels. 

Young We have data showing that induction of a Ca2+ wave in cultured myometrial cells that lack L-type Ca2+ channels causes activation of Ca2+-activated K+ channels that we think are store-operated. This is just with passage of a Ca2+ wave without thapsigargin. 

Ca2+ enters cells via a number of plasma membrane channels which belong to three families (Figure 11.2) (i) voltage-gated channels (ii) ligand-gated channels and (iii) capacitative, or store-operated channels (SOCs). 

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