ISOLATION OF BLEPHARISMIN‐BINDING 200 kDa PROTEIN RESPONSIBLE FOR BEHAVIOR IN Blepharisma

Publisher Website
Google Scholar
Abstract
Abstract— The ciliated protozoan, Blepharisma, shows an avoidance reaction (step‐up photophobic response) in response to light stimulation. A profile of a gel‐permeation of a crude detergent‐solubilized sample of the cells resulted in several red‐colored fractions. Among these blepharismin‐containing fractions, the fractions III‐V did not contain amino acids. The peak of fraction II monitored by 580 nm absorbance was much smaller. A prominent peak appeared in fraction I, which contained a large amount of amino acids. The absorption spectrum of fraction I was well fitted to the action spectrum of the step‐up photophobic response, although free pigment (blepharismin) also fitted. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of this fraction resulted in a thicker band corresponding to molecular mass of 200 kDa. These results suggest that the 200 kDa chromoprotein (blepharismin‐protein complex) is responsible for the step‐up photophobic response in Blepharisma. The absorption spectrum of free chromophore dissociated from the chromophore‐protein complex was identical to free red pigment termed blepharismin. The absorption spectrum of the other fractions agreed with that of thin‐layer chromatography‐purified red pigment, indicating that the pigments contained in these fractions are free pigment dissociated from the chromophore‐protein complex.