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Comment
. 2010 May 1;588(Pt 9):1395-7.
doi: 10.1113/jphysiol.2010.188664.

Desensitization and models of receptor-channel activation

Chris Shelley  1 , Stuart G Cull-Candy
Affiliations
Comment

Desensitization and models of receptor-channel activation

Chris Shelley et al. J Physiol. .
No abstract available

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Figures

Figure 1
Figure 1. A scheme to explain the activation and desensitization of the ACh receptor
AChR′ corresponds to the ACh-bound, open channel state of the receptor, whilst ACh + R′ represents the receptor in the desensitized state.
Figure 3
Figure 3. Sequential and simultaneous reaction schemes considered and rejected
S represents the agonist (or substrate, by analogy with enzyme kinetics), A represents the receptor in its active state, and B the receptor in its desensitized state. The fast agonist binding step and subsequent opening of the receptor channel were condensed into a single step as they were assumed to be in equilibrium when compared with the relatively slow desensitization step.
Figure 2
Figure 2. Intracellular voltage recording of acetylcholine responses at the frog endplate
Reproduced from Katz & Thesleff (1957). The authors used twin-barrelled ionophoretic micropipettes; one barrel was used to apply long conditioning (desensitizing) ACh pulses while the second barrel provided brief test pulses of ACh. These test pulses allowed measurement of the time constants of onset of desensitization, and the subsequent recovery.
Figure 4
Figure 4. The two cyclical schemes proposed by Katz and Thesleff
From their data they determined that either of these schemes could account for their results, whilst noting that the scheme on the left would require an energy source to drive the non-reversible reactions.
See this image and copyright information in PMC

Comment on

References

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