Microvillar Photoreceptor Cells of Invertebrates

Stieve, H.

doi:10.1007/978-1-4684-5841-1_8

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…In Limulus ventral nerve photoreceptors a conformational change of a rhodopsin molecule, caused by absorption of a photon, triggers an enzmye cascade resulting in an increase in the concentration of a putative intracellular transmitter (Cone 1973;Becker et al 1988;Stieve 1989). Transmitter molecules bind to channel proteins, increase the open probability and depolarize the cell.…”

Section: Introductionmentioning

confidence: 99%

Light-activated single channel currents in Limulus ventral nerve photoreceptors

Nagy

Stieve

1990

Eur Biophys J

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Light-activated single channel currents were measured in Limulus ventral photoreceptors in the cellattached configuration at 14°C. The results show three channel types with conductances of 6.2, 10.4 and 28.7 pS. The most active channels have the 10 pS conductance; the open time histograms of these channels could be best fitted by the sum of two exponentials with time constants (and weights) of 0.58 ms (0.78) and 4.32 ms (0.22), suggesting two populations of channels or two open states. The mean open time was 1.38 ms.The open time histogram of the channels with the 29 pS conductance could be best fitted by a single exponential with a time constant of 3.35 ms. First latencies of the 10 pS channels were between 40 and 280 ms but those of the 29 pS conductance channels were > 300 ms. These findings suggest that the two channel types are gated by two different intracellular transmitters or mechanisms.

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Section: Introductionmentioning

confidence: 99%

Light-activated single channel currents in Limulus ventral nerve photoreceptors

Nagy

Stieve

1990

Eur Biophys J

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“…Upon absorbing a photon, the rhodopsin molecule changes its conformation to an active meta state, which triggers an enzyme cascade, resulting in an increase in the concentration of a putative intracellular transmitter in Limulus ventral nerve photoreceptors (Cone 1973;Fein and Payne 1989;Becker et al 1988;Stieve 1989). Transmitter molecules bind to channel proteins, causing their opening and leading to the depolarization of the photoreceptor cell.…”

Section: Introductionmentioning

confidence: 99%

Kinetic properties of single-ion channels activated by light in Limulus ventral nerve photoreceptors

Nagy

1990

Eur Biophys J

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Previous results on Limulus ventral photoreceptors have suggested that besides inositol trisphosphate, another unknown transmitter may also work in the transduction cascade. This assumption has been supported by the finding of two light-activated channel types. The present report furnishes further evidence of the dual transmitter mechanism in phototransduction by analyzing the kinetic properties and voltage dependency of these cation channels with conductances of ~12pS and ~30pS. Single-channel currents were recorded in Limulus ventral nerve photoreceptors in cell-attached configuration at 14 °C. At Vm~ + 80 mV, the open-time histograms of both channels were fit best by the sum of two exponentials; time constants (and weights) were: 0.81 ms (0.62) and 6.20 ms (0.38) for the 12 pS channels and 2.38 ms (0.43) and 19.4 ms (0.57) for the 30 pS channels. At this potential the mean open times were 2.7 ms for the 12pS and 13.3 ms for the 30 pS channels, about two-times larger than at hyperpolarizing potentials. The deactivation kinetics were also different for the two channels. The time constants of the decay of the channel activity, after switching off the light, were 2.5 s for the 12 pS and 12.9 s for the 30 pS channels. The 12 pS channel exhibits bursting and subconductance states at positive potentials. The subconductances are about 20%, 46% and 72% of the fully open state. Results show that the two types of light-activated channels have different kinetic parameters, voltage dependence and gating mechanisms. The two channels are suggested to be gated by different transmitters or processes. It is proposed that for the 30 pS channel the transmitter could be calcium ion or a calcium-dependent transmitter.

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Microvillar Photoreceptor Cells of Invertebrates

Cited by 2 publications

References 26 publications

Light-activated single channel currents in Limulus ventral nerve photoreceptors

Light-activated single channel currents in Limulus ventral nerve photoreceptors

Kinetic properties of single-ion channels activated by light in Limulus ventral nerve photoreceptors

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