| gamma efferent | The thin axon of a gamma motor neuron innervating the intrafusal muscle fibres of a muscle spindle. (05 Mar 2000) |
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| gamma emission | <physics> Nuclear decay process whereby the nucleus goes from an excited state to a more stable state by emitting a gamma ray. See: gamma ray. (09 Oct 1997) |
| gamma encephalography | Imaging of the encephalon by the administration of small amounts of gamma-emitting radionuclides; commonly called a brain scan; superseded by computed tomography and magnetic resonance imaging. (05 Mar 2000) |
| gamma-endorphin | <chemical> An endogenous opioid peptide derived from the pro-opiomelanocortin precursor peptide. It differs from alpha-endorphin by one amino acid. Chemical name: gamma-Endorphin (12 Dec 1998) |
| gamma fibres | Nerve fibre's that have a conduction rate of about 20 m/sec. See: gamma efferent. (05 Mar 2000) |
| gamma globulin | <immunology> A non-specific immunoglobulin (antibody) administered for the purpose of passive immunity. A common example is hepatitis A prophylaxis. (27 Sep 1997) |
| gamma-globulins | Serum globulins that migrate in the gamma region on electrophoresis. At one time, gamma-globulins came to be used as a synonym for immunoglobulins since most immunoglobulins are gamma globulins. But since some immunoglobulins exhibit an alpha or beta electrophoretic mobility, that usage is in decline. (12 Dec 1998) |
| gamma-glutamyl carboxylase | <enzyme> An enzyme that catalyses the formation of gamma-carboxyglutamyl residues in many proteins, several appearing in the blood clotting cascade. (05 Mar 2000) |
| gamma-glutamyl cycle | A proposed pathway for the glutathione-dependent transport of certain amino acids (most notably l-cystine, l-methionine, and l-glutamine) and dipeptides into certain cells; this cycle requires the formation of gamma-glutamyl amino acids and gamma-glutamyl dipeptides as well as a protein for the translocation of these di-and triisopeptides into the cells. (05 Mar 2000) |
| gamma-glutamylcyclotransferase | <enzyme> An enzyme that catalyses the synthesis of pyroglutamate from a gamma-glutamyl-amino acid, also releasing the free amino acid. The enzyme acts on derivatives of glutamate, 2-aminobutyrate, alanine and glycine. The enzyme has been proposed to have a role in a gamma-glutamyl cycle for amino acid transport into cells in the intestines. Chemical name: (5-L-Glutamyl)-L-amino-acid 5-glutamyltransferase (cyclizing) Registry number: EC 2.3.2.4 (12 Dec 1998) |
| gamma-glutamylcysteine | A necessary precursor in the biosynthesis of glutathione; contains an isopeptide rather than a eupeptide bond. Gamma-glutamylcysteine synthetase, an enzyme that catalyses the first step in glutathione biosynthesis, reacting l-glutamate, l-cysteine, and ATP to form gamma-glutamylcysteine, ADP, and orthophosphate; inhibited by thiols such as glutathione. (05 Mar 2000) |
| gamma-glutamyl dipeptidase | <enzyme> Removes glycine from leukotriene d4 to form leukotriene e4 Registry number: EC 3.4.13.- (26 Jun 1999) |
| gamma-glutamylhistamine synthetase | <enzyme> Incorporates histamine or other amines into peptide linkage with glutamate; from aplysia ganglia Registry number: EC 6.3.2.- Synonym: gamma-gha synthetase, gamma-glutamyl amine synthetase, gamma-glutamyl octopamine synthetase, gamma-glutamyl tyramine synthetase (26 Jun 1999) |
| gamma-glutamyl hydrolase | N-Pteroyl-l-glutamate hydrolase;an enzyme cleaving l-glutamyl residues from pteridine oligoglutamates; used in certain antitumour treatments. Synonym: carboxypeptidase G, conjugase, gamma-glutamate (glutamate gamma-) carboxypeptidase. (05 Mar 2000) |
| gamma-glutamyltransferase | <enzyme> An enzyme that catalyses reversibly the transfer of a glutamyl group from a glutamyl-peptide and an amino acid to a peptide and a glutamyl-amino acid. It is often elevated above normal in hepatitis and other conditions that cause chemical liver damage. Chemical name: (5-L-Glutamyl)-peptide:amino-acid 5-glutamyltransferase Registry number: EC 2.3.2.2 Acronym: GGT (12 Sep 2002) |