The PDZ assembled "transducisome" of microvillar photoreceptors: the TRP/TRPL problem.
Two types of ion channels, TRP and TRPL, are activated upon light-absorption in rhabdomeral photo-receptor membranes of fly compound eyes. Whereas TRP is associated with other signaling proteins into a multiprotein complex (transducisome), the molecular organization of TRPL is discussed controversely. We analysed the TRPL content of blowfly rhabdomeral membranes and investigated by co-immunoprecipitation studies whether or not TRPL is part of the transducisome. Compared to TRP there are at least ten times less TRPL molecules present in the rhabdomeral membrane. A small fraction of the total TRPL present co-immunoprecipitates with other proteins of the transducisome and vice versa. Our data suggest that a significant fraction of TRPL is not incorporated into the transducisome. This fraction may either form independent ion channels or bind to the transducisome transiently.
Department of Cell- and Neurobiology, University of Karlsruhe, Kornblumenstr. 13, 76128 Karlsruhe, Germany, , , , , , DE.
Reinhard
R
Paulsen
Department of Cell- and Neurobiology, University of Karlsruhe, Kornblumenstr. 13, 76128 Karlsruhe, Germany, , , , , , DE.
Monika
M
Bähner
Department of Cell- and Neurobiology, University of Karlsruhe, Kornblumenstr. 13, 76128 Karlsruhe, Germany, , , , , , DE.
Armin
A
Huber
Calliphora; INAD signaling complex TRP; Key words Transducisome; PDZ domains; TRPL; phototransduction Drosophila