Guanylate cyclases are enzymes that catalyze the conversion of guanosine triphosphate (GTP) into cyclic guanosine monophosphate (cGMP), belonging to the phosphodiesterase family. These enzymes possess unique catalytic sites and regulatory regions in their structure, typically located in the cytoplasm but can also be found on the cell membrane. Guanylate cyclases play roles in various biological responses and signaling pathways, including visual signal transduction, cardiovascular regulation, and neurotransmitter release. Their expression exhibits tissue specificity, primarily high in the retina, heart, and brain. Gene mutations can lead to various diseases, including certain genetic blindness and heart conditions, highlighting their importance in maintaining physiological functions.