Abstract: The soluble and membrane-bound protein in the photoreceptor of the Cherax quadricarinatus,which were extracted by common method of protein-extraction,respectively,were separated and identified with SDS-PAGE and western blotting.After dark adaptation and the illumination by sun-light and four kinds of different wavelength lights (red,green,blue,yellow),the content of the G-protein in the photoreceptor of C.quadricarinatus was analyzed with SDS-PAGE.The result of SDS-PAGE indicated:the numbers and the molecule mass of the protein bands in soluble and membrane fractions of the photoreceptor under different light conditions were basically similar,there was an apparent protein band at 42 Kd.The results of western blotting showed that anti-Gqα antibodies recognized the 42 Kd protein not only in the photoreceptor membrane but also in soluble fractions of the retina,the G-protein in the photoreceptor of C.quadricarinatus is a Gq-class G-protein.The content of two forms of Gqα,soluble Gqα and membrane-bound Gqα,changed depending on the light condition.The contents of the soluble Gqα were in turn,sun-light (7.71%)> yellow-light(7.32%)>red-light (7.06%)> dark adaptation(6.94%)> blue-light (6.46%)>green-light (5.74%);There was significantly different between red-light and yellow-light,very significantly different among others,except between dark-adapted and red-light.The content of the membrane-bound Gqα was contrary to the soluble Gqα.The contents of the membrane-bound Gqα were in turn,green-light (13.94%)> blue-light (10.56%)> dark-adapted (10.25%)> red-light (10.14%)> yellow-light (9.76%)> sun-light (9.44%);There was also significantly different between red-light and yellow-light,very significantly different among others,except between dark-adapted and red-light.These results indicate that the activation of the Gq-protein in the photoreceptor of C.quadricarinatus depends on the lights of different wavelength.The light sensitivity of the photoreceptor was different under different wavelength lights.