Calcium channels biophysical properties

The newest molecular addition to Cl- channels are bestrophins [5]. There are four different bestrophin isoforms in humans. Mutations in Bestl cause Best macular dystrophy, hence their name. All four isoforms induce chloride currents when expressed heterologously. Although they show a dependence on intracellular calcium, their biophysical properties differ from Ca-activated chloride currents typically observed in native cells. Mutagenesis experiments changed the activation of currents and induced slight changes in ion selectivity, lending support to the hypothesis that bestrophins themselves are Cl- channels. 

McRory JE, Hamid J, Doering CJ, Garcia E, Parker R, Hamming K, Chen L, Hildebrand M, Beedle AM, Feldcamp L, Zamponi GW, Snutch TP (2004) The CACNA1F gene encodes an L-type calcium channel with unique biophysical properties and tissue distribution. J Neurosci 24 1707-1718. 

We have reviewed the major calcium permeant ion channels in smooth muscle, summarized in Figure 8. The obvious complexity and redundancy of these channels almost certainly reflects evolutionary pressures associated with the diversity of functions subserved by smooth muscle. Progress in this area has generally proceeded by the identification and biophysical characterization of these channels using patch-clamp or bilayer techniques, followed by the determination of their molecular structure and regulatory properties. With the notable exception of metabotropic, nonse-... 

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