FIG. 1.

Formation of covalent protein-GMP complex by C. fasciculata extracts. (A) A C. fasciculata whole-cell extract was incubated with [α-³²P]GTP, and complex formation was analyzed directly by SDS-PAGE followed by autoradiography. (B) Nucleotide and magnesium specificity for the formation of covalent protein complexes. Aliquots from Mono S fractions containing either the 78- or the 116-kDa polypeptide were incubated with the indicated α-³²P-labeled nucleoside triphosphates in the presence (lanes 1, 3 to 5, 7, and 8) or absence (lanes 2 and 6) of 5 mM MgCl₂. Samples were analyzed by SDS-PAGE and visualized by autoradiography.