[Isoelectric focusing of rhodopsin]

By method of isoelectric focusing in polyacrylamide gel and sucrose density gradient it has been shown that rhodopsin preparation, obtained by different methods (including the rhodopsin with low content of lipids) are divided into a number of fractions with isoelectric points at the pH-range 5.4-6.0. The corresponding preparations of opsin show heterogeneity in pI, too. Heterogeneity in pI remains at denaturation conditions (8 M urea, 0.01% beta-mercaptoethanol, 1 mM EDTA). If separated in this system at least two protein components are detected. The nature of heterogeneity in pI found and its possible connection with complicated kinetics of the decay of early intermediate products of visual pigment are discussed.