A lobster phospholipase C-β that associates with G-proteins in response to odorants

A cDNA clone encoding a protein of 1116 amino acids with significant homology to β-isoforms of phospholipase C was isolated from lobster olfactory organ cDNA libraries and named lobPLCβ. This cDNA hybridized predominantly to a 9 kb transcript in RNA from olfactory organ, pereiopod, brain, and eye-eyestalk and to several smaller minor transcripts only in eye- eyestalk. An antiserum raised to the C terminus of lobPLCβ detected immunoreactivity in a single 130 kDa band in olfactory aesthetasc hairs, olfactory organ, pereiopod, dactyl, and brain. In eye-eyestalk this 130 kDa band was abundant, and minor bands of 100, 79, and 57 kDa also were detected. In cross sections of the aesthetasc hairs, immunoreactivity was detected in the outer dendritic segments of the olfactory receptor neurons, the site of olfactory transduction. A complex odorant caused lobPLCβ immunoreactivity to increase in membrane fractions and decrease in soluble fractions of homogenates of aesthetasc hairs. The odorant also increased the amount of lobPLCβ in immunoprecipitates of G(αq) and Gβ from homogenates of aesthetasc hairs. These results support the conclusion that lobPLCβ mediates olfactory transduction.