Guanosine-5'-triphosphate

Guanosine-5'-triphosphate (GTP) is a purine nucleotide that is significant in a variety of biological processes. It is one of the building blocks required for the synthesis of RNA during the transcription process. GTP also has roles in protein synthesis, signal transduction, and the G-protein signaling processes.

Structure

GTP is composed of the nitrogenous base guanine attached to the 1' carbon of a ribose sugar, which in turn is attached at the 5' position to a triphosphate group. The nitrogenous base, guanine, is a purine base, consisting of a six-membered and a five-membered nitrogen-containing ring fused to each other.

Function

GTP is involved in various biological processes:

• Transcription: GTP serves as a substrate for the synthesis of RNA during the transcription process.
• Protein synthesis: In protein synthesis, GTP is required for the binding of the aminoacyl tRNA to the ribosome.
• Signal transduction: GTP is involved in signal transduction pathways. It is used by G-proteins as a source of energy to switch between different functional states.
• G-protein signaling: GTP binds to G-proteins, causing a conformational change that allows the G-protein to act as a relay between different signaling proteins.

Metabolism

GTP is produced in the cytosol of the cell where it can be used directly or transported into the mitochondria for incorporation into RNA. GTP can be synthesized through a number of pathways, including the purine nucleotide cycle and the de novo synthesis pathway. In the purine nucleotide cycle, GTP is synthesized from xanthosine monophosphate (XMP). In the de novo synthesis pathway, GTP is synthesized from simple precursors such as amino acids and formate.

See also

• Guanosine diphosphate
• Guanosine monophosphate
• Adenosine triphosphate