Guanosine diphosphate

Guanosine diphosphate (GDP) is a nucleotide that is used as a source of energy or an activator of substrates in metabolic reactions, like the synthesis of RNA and DNA. It is also used in signal transduction pathways.

Structure

Guanosine diphosphate is composed of the purine base guanine, the five-carbon sugar ribose, and two phosphate groups. The phosphate groups are attached to the 5' carbon atom of the ribose sugar, and the guanine is attached to the 1' carbon atom of the ribosome sugar.

Function

GDP is involved in several cellular processes. It serves as a substrate for the synthesis of RNA and DNA, and it is used in the G-protein signaling pathway. In this pathway, the binding of a ligand to a G-protein coupled receptor causes the exchange of GDP for GTP on the G-protein, activating it.

Metabolism

GDP can be synthesized through several pathways. In the de novo pathway, it is synthesized from simple precursors through a series of enzymatic reactions. In the salvage pathway, it is synthesized from guanosine or guanine, which are recycled from degraded RNA and DNA.

GDP can be converted to GTP by the enzyme nucleoside diphosphate kinase, which catalyzes the transfer of a phosphate group from a triphosphate (like ATP) to a diphosphate (like GDP).

See also

• Nucleotide
• Guanosine triphosphate
• G-protein
• Nucleoside diphosphate kinase