Appearance of a novel Ca2+ influx pathway in Sf9 insect cells following expression of the transient receptor potential-like (trpl) protein of Drosophila.
Activation of phospholipase C, elevation of free cytosolic Ca2+ concentration ([Ca2+]i) and stimulation of Ca2+ influx have been implicated in Drosophila phototransduction. Electrophysiological studies suggest that trp and trpl proteins may be important for the light-activated Ca2+ current found in Drosophila photoreceptor cells. Although these proteins exhibit homologies to voltage-gated Ca2+ and Na+ channels, their actual function in insect cells and their relation to proteins involved in mammalian cell Ca2+ signaling remains unknown. In the present study, [Ca2+]i was examined in fura-2-loaded Sf9 insect cells infected with recombinant baculovirus containing cDNA for the trpl protein. Ca2+ influx was examined by use of Ba2+, a Ca2+ surrogate that is not a substrate for Ca(2+)-pumps or carriers and by measurement of whole-cell membrane currents. The results suggest that expression of trpl is associated with appearance of a Ca2+ permeable, non-selective cation channel formed by the trpl protein.
Hu
Y
Y
Depts. of Molecular Physiology, Baylor College of Medicine, Houston, TX 77030.
Vaca
L
L
Zhu
X
X
Birnbaumer
L
L
Kunze
D L
DL
Schilling
W P
WP
D000818:Animals; D001464:Barium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000096:biosynthesis / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D004330:Drosophila / Q000378:metabolism*; D029721:Drosophila Proteins; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000096:biosynthesis / Q000502:physiology*; D009036:Moths; D011976:Receptors, Muscarinic / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D014162:Transfection; D050051:Transient Receptor Potential Channels
D002148:Calmodulin-Binding Proteins; D029721:Drosophila Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D011976:Receptors, Muscarinic; D011994:Recombinant Proteins; D050051:Transient Receptor Potential Channels; C074192:trpl protein, Drosophila; D001464:Barium; D002217:Carbachol; D002118:Calcium