Guanine Nucleotides

Nucleotides are small molecules composed of three parts, a nitrogenous base, a sugar and one or more phosphates. Nucleotides play many roles in cells. They are the precursors for the nucleic acids. ATP, a nucleotide, is the primary energy currency in a cell.  Nucleotides are also used as regulatory molecules (as is the case here).

The structure of guanosine triphosphate (GTP) is shown here:

	Model:

Guanosine diphosphate (GDP) has only two phosphate groups.