BioPHYSICAL chemistry
during steps 1 and 2 (Figure 17.11). The protein then switches, due to conformational changes, to be coupled to the other side o ...
located at very similar positions, the loops connecting the helices differ. The domains in the extramembraneous regions are thou ...
an exterior surface that has significant electrostatic character, which serves to interact with a chloride ion, allowing putativ ...
Rhodopsin proteins in visual response Much of the characterization of the visual process has centered in rhodopsin in rod cells. ...
Problems 17.1 Why do rod cells respond to light? 17.2 What are the roles of GMP and transducin in vision? 17.3 What is the initi ...
17.9 How were cubic lipid phases important for the determination of the structure of bacteriorhodopsin? 17.10 What questions rem ...
Membrane potentials The cell membrane is a lipid bilayer. The composition of cell membranes varies among cell types and growth c ...
virtually every animal cell, the fluid surrounding the cells has ion con- centrations that are different from those found in the ...
and urea from the inside to the outside of a cell (this is not actually found in nature). The coupled reaction would be written ...
because there is a passive glucose channel that allows the glucose to pass from the epithelial cells into the bloodstream. In th ...
Under normal cellular conditions, it takes very little transfer of protons across the membrane before the electric potential ΔVt ...
in the mammalian central nervous system is the amino acid glutamate. Glutamate transporters transport three Na+ions and one prot ...
The availability of several different structures of porins has provided a molecular basis for the conductance of molecules in tr ...
Whereas these structures provide insight into the molecular mechanism of transport, many questions remain. For example, how are ...
transport in a channel is usually gated; that is, the channel is open or closed depending on another factor. The controlling fac ...
CHAPTER 18 MEMBRANE POTENTIALS 399 (a) KcsA MscL (b) (c) 20 A° (d) Figure 18.8Structures of two ion channels. (a,c) The KcsA pot ...
The potassium channel is a voltage-gated channel that can have up to six transmembrane helices. Only two are found for the bacte ...
a domino effect. In addition, the dipoles of small helices appear to contribute electrostatically to the selectivity, with the d ...
but cannot serve as a channel since the protein does not possess any trans- membrane domains. The sequence of this protein is ho ...
Problems 18.1 The lipid bilayer is permeable to what type of small molecules? 18.2 Consider a cell membrane at 298 K which has g ...
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