Catalyzes the irreversible NADPH-dependent deamination of GMP to IMP. It functions in the conversion of nucleobase, nucleoside and nucleotide derivatives of G to A nucleotides, and in maintaining the intracellular balance of A and G nucleotides ( , ). Plays a role in modulating cellular differentiation .
Highly expressed in heart, skeletal muscle, kidney, brain, liver, prostate, spleen, placenta, testis and ovary. Low expression in colon, thymus and peripheral blood leukocytes.