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Abstract:
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Delgado R, Bacigalupo J. Unitary recordings of TRP and TRPL
channels from isolated Drosophila retinal photoreceptor rhabdomeres:
activation by light and lipids. J Neurophysiol 101: 2372–2379, 2009.
First published March 4, 2009; doi:10.1152/jn.90578.2008. Transient
receptor potential (TRP) channels play key roles in sensory transduction.
The TRP family founding members, the Drosophila lightdependent
channels, were previously studied under voltage clamp, but
had not been characterized in intact rhabdomeres at single-channel
level. We report patch-clamp recordings from intact isolated photoreceptors
of wt and mutant flies lacking TRP (trp343), TRPL (trpl302),
or both channels (trp313; trpl302). Unitary currents were activated by
light in rhabdomere-attached patches. In excised rhabdomeral patches,
the channels were directly activated by molecules implicated in
phototransduction, such as diacylglycerol and polyunsaturated fatty
acids. Currents recorded from trpl photoreceptors are blocked by
external Ca2 , Mg2 (1 mM), and La3 (20 M), whereas those from
trp photoreceptors are not. Rhabdomeric patches lacked voltagedependent
activity. Patches from trp;trpl mutants were devoid of
channels. These characteristics match the macroscopic conductances,
suggesting that the unitary currents from Drosophila trpl and trp
photoreceptors correspond to TRP and TRPL. |