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Olfactory perireceptor and receptor events in moths: a kinetic model revised.

Kaissling KE - J. Comp. Physiol. A Neuroethol. Sens. Neural. Behav. Physiol. (2009)

Bottom Line: This is compared with the estimated densities of the sensory-neuron membrane protein and of ion channels.The EC(50) of the model pheromone-PBP complex interacting with the receptor molecules is 6.8 muM, as compared with the EC(50) = 1.5 muM of bombykol recently determined using heterologous expression.A possible mechanism widening the range of stimulus intensities covered by the dose-response curve of the receptor-potential is proposed.

View Article: PubMed Central - PubMed

Affiliation: Max-Planck-Institut fuer Verhaltensphysiologie/Ornithologie, Seewiesen, 82319, Starnberg, Germany. Kaissling@orn.mpg.de

ABSTRACT
Modelling reveals that within about 3 ms after entering the sensillum lymph, 17% of total pheromone is enzymatically degraded while 83% is bound to the pheromone-binding protein (PBP) and thereby largely protected from enzymatic degradation. The latter proceeds within minutes, 20,000-fold more slowly than with the free pheromone. In vivo the complex pheromone-PBP interacts with the receptor molecule. At weak stimulation the half-life of the active complex is 0.8 s due to the postulated pheromone deactivation. Most likely this process is enzymatically catalysed; it changes the PBP into a scavenger form, possibly by interference with the C-terminus. The indirectly determined PBP concentration (3.8 mM) is close to direct measurements. The calculated density of receptor molecules within the plasma membrane of the receptor neuron reaches up to 6,000 units per mum(2). This is compared with the estimated densities of the sensory-neuron membrane protein and of ion channels. The EC(50) of the model pheromone-PBP complex interacting with the receptor molecules is 6.8 muM, as compared with the EC(50) = 1.5 muM of bombykol recently determined using heterologous expression. A possible mechanism widening the range of stimulus intensities covered by the dose-response curve of the receptor-potential is proposed.

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Parameters of model R (Fig. 3). The parameters different from Fig. 4 are k5R, Kd5R, k8R, Km5,8, and RtotR. The parameters Ntot, k7, and k−7 are absent
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Fig5: Parameters of model R (Fig. 3). The parameters different from Fig. 4 are k5R, Kd5R, k8R, Km5,8, and RtotR. The parameters Ntot, k7, and k−7 are absent

Mentions: Reaction network, chemical model R, with the receptor molecule catalyzing the deactivation of the complex FA. For explanations see Fig. 2. For model parameters see Fig. 5


Olfactory perireceptor and receptor events in moths: a kinetic model revised.

Kaissling KE - J. Comp. Physiol. A Neuroethol. Sens. Neural. Behav. Physiol. (2009)

Parameters of model R (Fig. 3). The parameters different from Fig. 4 are k5R, Kd5R, k8R, Km5,8, and RtotR. The parameters Ntot, k7, and k−7 are absent
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2749182&req=5

Fig5: Parameters of model R (Fig. 3). The parameters different from Fig. 4 are k5R, Kd5R, k8R, Km5,8, and RtotR. The parameters Ntot, k7, and k−7 are absent
Mentions: Reaction network, chemical model R, with the receptor molecule catalyzing the deactivation of the complex FA. For explanations see Fig. 2. For model parameters see Fig. 5

Bottom Line: This is compared with the estimated densities of the sensory-neuron membrane protein and of ion channels.The EC(50) of the model pheromone-PBP complex interacting with the receptor molecules is 6.8 muM, as compared with the EC(50) = 1.5 muM of bombykol recently determined using heterologous expression.A possible mechanism widening the range of stimulus intensities covered by the dose-response curve of the receptor-potential is proposed.

View Article: PubMed Central - PubMed

Affiliation: Max-Planck-Institut fuer Verhaltensphysiologie/Ornithologie, Seewiesen, 82319, Starnberg, Germany. Kaissling@orn.mpg.de

ABSTRACT
Modelling reveals that within about 3 ms after entering the sensillum lymph, 17% of total pheromone is enzymatically degraded while 83% is bound to the pheromone-binding protein (PBP) and thereby largely protected from enzymatic degradation. The latter proceeds within minutes, 20,000-fold more slowly than with the free pheromone. In vivo the complex pheromone-PBP interacts with the receptor molecule. At weak stimulation the half-life of the active complex is 0.8 s due to the postulated pheromone deactivation. Most likely this process is enzymatically catalysed; it changes the PBP into a scavenger form, possibly by interference with the C-terminus. The indirectly determined PBP concentration (3.8 mM) is close to direct measurements. The calculated density of receptor molecules within the plasma membrane of the receptor neuron reaches up to 6,000 units per mum(2). This is compared with the estimated densities of the sensory-neuron membrane protein and of ion channels. The EC(50) of the model pheromone-PBP complex interacting with the receptor molecules is 6.8 muM, as compared with the EC(50) = 1.5 muM of bombykol recently determined using heterologous expression. A possible mechanism widening the range of stimulus intensities covered by the dose-response curve of the receptor-potential is proposed.

Show MeSH