Voltage dependent function

So how do the foot structures effect the release of Ca from the terminal cisternae of the SR The feet that join the t-tubules and the terminal cis-ternae of the SR are approximately 16 nm thick. The feet apparently function by first sensing either a voltage-dependent conformation change (skeletal mus-... 

More recent analysis of tissue specific gene deletions showed that the Cav1.2 channel is involved in a wide variety of function including hippocampal learning, insulin secretion, intestine and bladder motility. Further analysis will be required to unravel the functional significance of voltage-dependent calcium channels for specific cellular functions. 

Hofmann F, Lacinova L, Klugbauer N (1999) Voltage-dependent calcium channels from structure to function. Rev Physiol Biochem Pharmacol 139 33-87... 

Voltage-dependent gating requires voltage-dependent conformational changes in the protein component(s) of ion channels 100 Pharmacological agents acting on ion channels help define their functions 101... 

There are at least five different types of voltage-dependent Ca2+ channel molecules, differing in their gating kinetics, modes of Ca2+-inactivation and Ca2+-iregulation, and sensitivity to specific marine toxins [13] (see Ch. 6). The distinctions between the types of channel are of considerable interest because the different subtypes are believed to subserve different cellular functions. For example, the control of neurotransmitter release in peripheral sympathetic neurons appears to be under the predominant control of N-type calcium channels. 

Although Li+ appears to have no nutritional function, plants have the ability to absorb the cation, the uptake being inhibited by Ca2+ [248], The transport of Li+ in plant cells has received little attention its movement can be passive or mediated by Na+ channels [249] and in some reports Li+ actually blocks ion channels for instance it inhibits voltage-dependent K+ channels in Chara cells [250]. Li+ is unevenly distributed throughout the plant, being most concentrated in the cell walls [251]. 

Helliwell RM, Large WA 1997 Alphal-adrenoceptor activation of a non-selective cation current in rabbit portal vein by 1,2-diacyl-sn-glycerol. J Physiol 499 417-428 Hofmann F, Lacinova L, Klugbauer N 1999 Voltage-dependent calcium channels from structure to function. Rev Physiol Biochem Pharmacol 139 33—87 Hofmann T, Schaefer M, Schultz G, Gundermann T 2000 Transient receptor potential channels as molecular substrates of receptor-mediated cation entry. J Mol Med 78 14—25 Inoue R, Okada T, Onoue H et al 2001 The transient receptor potential protein homologue TRP6 is the essential component of vascular aj-adrenoceptor-activated Ca2+-permeable cation channel. Circ Res 88 325—332... 

Arii T, Ohyanagi M, Shibuya J, Iwasaki T 1999 Increased function of the voltage-dependent calcium channels, without increase of Ca2+ release from the sarcoplasmic reticulum in the arterioles of spontaneous hypertensive rats. Am J Hypertens 12 1236-1242 Attree O, Olivos IM, Okabe I et al 1992 The Lowe s oculocerebrorenal syndrome gene encodes a protein highly homologous to inositol polyphosphate-5-phosphatase. Nature 358 239-242 Brading AF, Turner WH 1994 The unstable bladder towards a common mechanism. Br J Urol 73 3-8... 

The sodium channels consist of a highly processed a subunit (260 kDa) associated with auxiliary p subunits. The pore-forming a subunit is sufficient for functional expression, but the kinetics and voltage dependence of channel gating are modified by the p subunits. The transmembrane organization is shown in Figure 9.5. The a subunit is organized in four... 

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