Guanylate Kinase

Guanylate kinase is an enzyme that catalyzes the reaction below:

GMP + ATP <=> GDP + ADP

A similar reaction is catalyzed by adenylate kinase (see here also). The guanylate kinase-catalyzed reaction is part of de novo purine biosynthesis and can occur as part of purine salvage synthesis as well.

See also: De Novo Biosynthesis of Purine Nucleotides, Salvage Routes to Deoxyribonucleotide Synthesis