HUMAN GUANYLATE KINASE (GUK1) - CDNA SEQUENCE, EXPRESSION AND CHROMOSOMAL LOCALIZATION

Guanylate kinase (GK) catalyses the conversion of GMP to GTP as part o f the cGMP cycle, In mammalian phototransduction, this cycle is essent ial for the regeneration of cGMP following its hydrolysis by phosphodi esterase, Mutations in different parts of this signalling cascade lead to retinal degeneration in humans, Protein studies have localized a l ocus for GK to a region of human chromosome 1 that also contains an au tosomal recessive form of retinitis pigmentosa (RP12) and Usher's type 11a (USH2A). We report the sequence of this human GK (GUK1) and a fur ther refinement of its localization to 1q32-41, placing it in the same interval as USH2A.