Catalyzes the phosphorylation of GMP to GDP. Essential enzyme for recycling GMP and indirectly, cyclic GMP (cGMP) . Involved in the cGMP metabolism in photoreceptors (By similarity). It may also have a role in the survival and growth progression of some tumors . In addition to its physiological role, GUK1 is essential for convert prodrugs used for the treatment of cancers and viral infections into their pharmacologically active metabolites, most notably acyclovir, ganciclovir, and 6-thioguanine and its closely related analog 6-mercaptopurine ( ).
Subcellular locations: Photoreceptor inner segment, Cytoplasm, Cytosol
Colocalizes with RD3 in photoreceptor inner segments and to a lesser extent in the outer plexiform layer.
Widely expressed.