Ion channels, G-proteins

Ion channels. G proteins are also involved in the coupling of some receptors to ion channels. A classic example is the modulation of inwardly rectifying potassium channels by m2 acetylcholine receptors. Other receptors have been shown to modulate Ca and/or K channels by either G protein a or Py subunits. 

Voltage-gated ion channels Ligand-gated ion channels G-proteins... 

Ligand-gated ion channels G protein-coupled receptors Receptors with intrinsic enzyme activity INTRODUCTION... 

The major drawback of these models, however, is their lack of a clear reference between model components and constituent parts of the biological system (e.g. structures like ion channels, transporter proteins, receptors, etc.). These models, therefore, do not permit the simulation of patho-physiological detail, such as the series of events that follows a reduction in oxygen supply to the cardiac muscle and, ultimately, causes serious disturbances in heart rhythm. 

Smart, T. G. Regulation of excitatory and inhibitory neuro-transmitter-gated ion channels by protein phosphorylation. Curr. Opin. Neurobiol. 7 358-367,1997. 

Ion Channels. In addition to the action of protein kinases that phosphorylatc ion channels and modify ion conductance. G proteins are coupled directly to ion channels to legulate their action. The (Ta channel on the cell mem-htanc is activated by G proteins without the need of a second messenger to allow CV to enter the cell. The a subunit of... 

Ligand-gated ion channels) (G-coupled protein/second messenger)... 

Whereas the main challenge for the first bilayer simulations has been to obtain stable bilayers with properties (e.g., densities) which compare well with experiments, more and more complex problems can be tackled nowadays. For example, lipid bilayers were set up and compared in different phases (the fluid, the gel, the ripple phase) [67,68,76,81]. The formation of large pores and the structure of water in these water channels have been studied [80,81], and the forces acting on lipids which are pulled out of a membrane have been measured [82]. The bilayer systems themselves are also becoming more complex. Bilayers made of complicated amphiphiles such as unsaturated lipids have been considered [83,84]. The effect of adding cholesterol has been investigated [85,86]. An increasing number of studies are concerned with the important complex of hpid/protein interactions [87-89] and, in particular, with the structure of ion channels [90-92]. 

---