Nucleotide exchange factors (NEFs) are
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
s that stimulate the exchange (replacement) of
nucleoside
Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase (also termed a nitrogenous base) and a five-carbon sugar (ribose or 2'-deoxyribose) whereas a nucleotid ...
diphosphate
In chemistry, pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate () and tetrasodium pyrophosphate (), among others. Often pyrophosphate ...
s for nucleoside
triphosphates bound to other proteins.
Function
Many cellular proteins cleave (
hydrolyze) nucleoside triphosphates –
adenosine triphosphate
Adenosine triphosphate (ATP) is a nucleoside triphosphate that provides energy to drive and support many processes in living cell (biology), cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known ...
(ATP) or
guanosine triphosphate
Guanosine-5'-triphosphate (GTP) is a purine nucleoside triphosphate. It is one of the building blocks needed for the synthesis of RNA during the transcription process. Its structure is similar to that of the guanosine nucleoside, the only di ...
(GTP) – to their diphosphate forms (
ADP and
GDP) as a source of energy and to drive conformational changes. These changes in turn affect the structural,
enzymatic, or signalling properties of the protein.
Nucleotide exchange factors actively assist in the exchange of depleted nucleoside diphosphates for fresh nucleoside triphosphates. NEFs are specific for the nucleotides they exchange (ADP or GDP, but not both) and are often specific to a single protein or class of proteins with which they interact.
See also
*
Nucleoside-diphosphate kinase
Nucleoside-diphosphate kinases (NDPKs, also NDP kinase, (poly)nucleotide kinases and nucleoside diphosphokinases) are enzymes that catalyst, catalyze the exchange of terminal phosphate between different nucleotide, nucleoside diphosphates (NDP) a ...
*
Guanine nucleotide exchange factor
Guanine nucleotide exchange factors (GEFs) are proteins or protein domains that activate monomeric GTPases by stimulating the release of guanosine diphosphate (GDP) to allow binding of guanosine triphosphate (GTP). A variety of unrelated structu ...
References
External links
Alfred Wittinghofer's Seminar: GTP-Binding Proteins as Molecular Switches
Proteins
Articles containing video clips
{{Protein-stub