Protein channels

Protein acidulant Protein additives Protein ammo acids a-l-Proteinase inhibitor Protein-based mimetics Protein Ca [42617-41-4] Protein channels Protein chromatography Protein crystal growth... 

Ion channels that are opened by binding of a neurotransmitter (or drug) to a receptor domain on extracellular sites of the channel protein(s) are defined... 

Multifunctional protein complex in the ER membrane. It translocates secretoiy proteins across and integrates membrane proteins into the ER membrane. The proteinconducting channel protein Sec61p is the most important component of the translocon. 

For all other members of the TRP family it still has to be shown whether the presumptive pore loop or other protein domains actually line the ion conducting pathway of the channel. Based on the results showing that expression of most TRPC channels yields currents carried by Na+and Ca2+, and that expression of TRPM4 and TRPM7 channels yields currents carried by Na+ but not by Ca2+(TRPM4) or even currents carried by Mg2+or Ca2+(TRPM7), it seems likely that the pore structures of these channel proteins vary considerably. 

Minke B, Cook B (2002) TRP channel proteins and signal transduction. Physiol Rev 82 429-472... 

The voltage sensor is the part of a channel protein responsible for detection of the membrane potential. A voltage sensor of the voltage-dependent Na+ channel was predicted by Hodgkin and Huxley in 1952. Positively charged amino acid residues in S4 of each repeat play an essential role as the voltage sensor. 

Hagiwara T, Kijima-Suda I, Ido T, Ohrui H, Tomita K (1994) Inhibition of bacterial and viral sialidases by 3-fluoro-V-acetyIneuraminic acid, Carbohydr Res 263 167-172 Haskell TH, Peterson FE, Watson D, Plessas NR, Culbertson T (1970) Neuraminidase inhibition and viral chemotherapy, J Med Chem 13 697-704 Hatakeyama S, Sugaya N, Ito M, Yamazaki M, Ichikawa M, Kimura K, Kiso M, Shimizu H, Kawakami C, Koike K, Mitamura K, Kawaoka Y (2007) Emergence of influenza B viruses with reduced sensitivity to neuraminidase inhibitors, JAMA 297 1435-1442 Hay AJ (1992) The action of adamantanamines against influenza A viruses inhibition of the M2 ion channel protein, Semin Virol 3 21-30... 

Indeed, the resistance problem has sometimes been severe enough to threaten a loss of control over the pest. A study of a number of resistant strains from the field has revealed two major types of resistance mechanism. Some individuals possess aberrant forms of the target site, the Na" channel. At least two forms are known that confer either kdr (<100-fold) or super kdr (>100-fold) resistance, which is the consequence of the presence of insensitive forms of the Na+ channel protein (McCaffery 1998, and Chapter 4, Section 4.4 of this book). 

The common denominator of all these CP-channel blockers (Fig. 2) is their acidic function (usually carboxylate), the secondary amine with a certain spacing to the acidic group, a nitro substitution at a certain distance from the carboxylate group, and the apolar groups such as the phenyl-propyl-residue. We have suggested that the interaction with the CP-channel requires all of these interaction sites, and that even the apolar moiety of the blocker molecule reacts with the channel protein rather than with the membrane lipid [70]. 

At this time, more then thirty channel DNAs have been cloned and characterized from various sources, predominantly from Drosophila melanogaster, mouse, rat and human cDNA/genomic libraries [6-31]. Inspection of the derived primary K channel protein sequences indicates that voltage-gated channels belong to a... 

Historically the Shaker (Sh) K channel was the first K channel which was cloned and characterized [6-10]. Subsequently many more channel cDNAs and genes have been isolated and studied. Yet Sh channels remained in the forefront of channel research. The study of Sh channel mutants has provided the most thorough insight into structure-function relationships of K channels to date. I will first discuss in this chapter the primary sequences of voltage-gated channels. I will only use a few selected examples for discussion. As of this time, so many related K channel protein sequences have been published that it is not feasible to discuss all of them. Subsequently, I will describe in detail the present knowledge about functional K" " channel domains which are implicated in activation, inactivation and selectivity of the channel. 

Fig. 4. Schematic organization of the Shaker K channel gene. The coordinates of the physical map are as in [9]. The direction of transcription is indicated by arrows. Approximate location of exons is given by boxes. Open box corresponds to noncoding exons, lettered boxes to alternative amino-terminal ends of Shaker channel proteins and the core region, respectively, numbered boxes to the two alternative carboxy-terminal ends. Exon numbers are as in [53].

This chapter s brief review has already described some mechanisms from which the diversity of K channel function, as evident at the level of biophysical and pharmacological studies, may arise. The multiplicity of different channel protein encod-... 

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