Potassium channels functional properties

Kv 3 -subunits are auxiliary subunits of Shaker-related Kv-channels, which belong to the Kvl subfamily of voltage-gated potassium channels. Kv(3 -subunits may function as chaperones in Kva -subunit assembly and may modulate the gating properties of Kv-channels. In particular, some Kv(3 -subunits may confer a rapid inactivation to otherwise non-inactivating Kv-channels. 

Table II summarizes properties of G proteins, assuming that Gs is functionally an activator of adenylyl cyclase and Ca2+ channels (see below) G( is functionally an inhibitor of adenylyl cyclase and activator of potassium channels (Gk), and G0 is functionally an activator of phospholipase C and an inhibitor of calcium channels [69]. Roles of /3y complexes are also assigned. However, the mere existence of this...

Wang J, Della Penna K, Wang H, Karczewski J, Connolly TM, Koblan KS, Bennett PB, Salata JJ (2003) Functional and pharmacological properties of canine ERG potassium channels. Am J Physiol-Heart circulat Physiol 284(1) H256-H267... 

This chapter will examine the properties (structure, distribution), pharmacology (openers and blockers as tools to study K+ channels) of calcium and potassium channels. Emphasis will be on integration of the information to develop a picture of the physiological roles of the different types of ion channels. Since potassium channels regulate arterial smooth muscle function by controlling membrane potential, the membrane potential and its relationship to smooth muscle function will be discussed first, as well as the role that K" channels play in controlling membrane potential. 

Fox AJ, Barnes PJ, Urban L, Dray A (1993) An in vitro study of the properties of single vagal afferents innervating guinea-pig airways. J Physiol (Lond) 469 21-35 Fox AJ, Barnes PJ, Venkatesan P, Belvisi MG (1997) Activation of large conductance potassium channels inhibits the afferent and efferent function of airway sensory nerves in the Guinea pig. JChn Invest 99 513-519... 

It is also possible to prepare crystalline electrides in which a trapped electron acts in effect as the anion. The bulk of the excess electron density in electrides resides in the X-ray empty cavities and in the interconnecting channels. Structures of electri-dides [Li(2,l, 1-crypt)]+-e [K(2,2,2-crypt)]+-e, [Rb(2,2,2-crypt)]+-e, [Cs(18-crown-6)2]+ e , [Cs(15-crown-5)2]+-e and mixed-sandwich electride [Cs(18-crown-6)(15-crown-5) e ]6 l8-crown-6 are known. Silica-zeolites with pore diameters of 7 A have been used to prepare silica-based electrides. The potassium species contains weakly bound electron pairs which appear to be delocalized, whereas the cesium species have optical and magnetic properties indicative of electron localization in cavities with litde interaction between the electrons or between them and the cation. The structural model of the stable cesium electride synthesized by intercalating cesium in zeolite ITQ-4 has been confirmed by the atomic pair distribution function (PDF) analysis. The synthetic methods, structures, spectroscopic properties, and magnetic behavior of some electrides have been reviewed. Theoretical study on structural and electronic properties of inorganic electrides has also been addressed recently. ... 

The question arises now, that given these properties of sodium and potassium ions, how do ion channels recognise them, distinguish between them, and let the one or the other pass through them with high selectivity, as required for their proper physiological functioning. 

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