the guanine nucleotide-binding site , which can be resolved by high performance liquid chromatography procedures and identified by a photolyzable gtp analogue , is associated with a 21,000-dalton protein ( gp alpha ) that copurifies with beta gamma-subunits indistinguishable from the beta gamma-subunits associated with gs and gi .
C0018328
guanine nucleotide
C0018353
gtp