Guanylate Cyclase Activator 1C (GUCA1C)

Guanylate cyclase activators (GUCAs) are Ca(2+)-binding proteins that belong to the calmodulin superfamily. Absorption of light by rhodopsin leads to a decrease in intracellular concentration of cGMP and Ca(2+). GUCAs are activated by the decrease in Ca(2+) and stimulate guanylate cyclase (GC) to increase cGMP concentration.

The GUCA1C cDNA encodes a deduced 209-amino acid protein with 57% and 49% amino acid similarity to GUCA1A and GUCA1B, respectively, and a calculated molecular mass of 23.8 kD. Like other GUCAs, GUCA1C contains a putative N-myristoylation site at gly2 and 3 putative EF-hand motifs involved in Ca(2+) binding. Northern blot analysis detected a 1.3-kb GUCA1C transcript primarily in retina. GUCA1C has the same exon and intron structure as GUCA1A and GUCA1B.