Identification of cyclic guanosine monophosphate-binding proteins in Drosophila by direct photoaffinity labeling

Abstract

A procedure for direct photoaffinity labeling with [ 32P]cGMP has been used to identify cGMP-binding proteins in Drosophila. This method provides better sensitivity and resolution than previously described direct methods, because the proteins can be visualized by autoradiography following sodium dodecyl sulfate-gel electrophoresis. Labeling is observed with cGMP concentrations as low as 4 × 10 −8 m and is specific for cGMP. The sensitivity of the technique is sufficient to permit detection of cGMP-binding proteins in crude extracts. With this technique a single cytoplasmic cGMP-binding protein of subunit M r 108,000 has been identified in Drosophila embryos and cultured cells.