Cyclic Guanosine Monophosphate, or cGMP, is a nucleotide that plays a crucial role in cellular signaling. It is synthesized from Guanosine Triphosphate (GTP) by the enzyme guanylate cyclase. cGMP acts as a second messenger, helping to transmit signals within cells, particularly in response to hormones and neurotransmitters. cGMP is involved in various physiological processes, including smooth muscle relaxation, blood vessel dilation, and neurotransmission. It also regulates the activity of certain proteins and enzymes, influencing processes like cell growth and apoptosis. Overall, cGMP is essential for maintaining normal cellular functions and responses.