Modifies a noun

• nucleotide: The enzyme is modulated by adenine and guanine nucleotides, although it is difficult to make much sense of the observed effects.

• exchange: Ras associates with SOS, a guanine exchange factor, and exchanges GDP for GTP.

• factor: Ras associates with SOS, a guanine exchange factor, and exchanges GDP for GTP.

• base: There was no evidence of oxygen free radicals damaging the guanine bases in either gene.

• nucleotide-binding: Professor Graeme Milligan Studies of signal transduction mediated by guanine nucleotide-binding proteins.

• amine: A guanine amine at this same position would push the drug away; hence its AT specificity.