| acceptor site | The ribosomal binding site for the aminoacyl-tRNA during protein synthesis. (05 Mar 2000) |
|---|---|
| acceptor splicing site | Boundary between the right end of an intron and the left end of the adjacent exon. Synonym: acceptor splicing site. (05 Mar 2000) |
| active site | <chemistry> A specific region of an enzyme where a substrate binds and catalysis takes place (binding site). (06 May 1997) |
| alanine-trna ligase | <enzyme> An enzyme that activates alanine with its specific transfer RNA. Chemical name: L-Alanine:tRNA(Ala) ligase (AMP-forming) Registry number: EC 6.1.1.7 (12 Dec 1998) |
| allosteric site | A specific site on a multi-subunit enzyme or other protein that is not the substrate binding site, but that when reversibly bound by an effector, induces a conformational change in the protein, altering its catalytic or binding properties. (12 Dec 1998) |
| amidation site | <molecular biology> A C terminus consensus sequence, required for C terminus amidation of peptides. Consensus is glycine, followed by 2 basic amino acids (arg or lys). (18 Nov 1997) |
| aminoacid-tRNA ligases | Recommended name for aminoacyl-tRNA synthetases, e.g., tyrosine-tRNA ligase for tyrosyl-tRNA synthetase. (05 Mar 2000) |
| aminoacyl-tRNA | <molecular biology> The name of the complex created when a tRNA molecule is attached to its specific amino acid and ready to participate in protein synthesis. (13 Oct 1997) |
| amino acyl-tRNA ligases | <enzyme> Any of the group of ligases that catalyses the ATP-driven formation of a bond between an amino acid and a trna, activating the amino acids as a step in protein synthesis. Individual enzymes are highly specific for one amino acid and for any trna corresponding to that amino acid. Registry number: EC 6.1.1. (12 Dec 1998) |
| aminoacyl-tRNA synthetases | <enzyme> Enzymes catalyzing the formation of a specific aminoacyl-tRNA from an amino acid and adenosine 5'-triphosphate with the concomitant formation of adenosine 5'-monophosphate and pyrophosphate. Synonym: amino acid activating enzyme, aminoacyl-tRNA ligases. (05 Mar 2000) |
| antibody combining site | <immunology> In immune network theory, an idiotope, an antigenic site of an antibody that is responsible for that antibody binding to an antigenic determinant (epitope). Also used of the site on a ligand molecule to which a cell surface receptor binds. (18 Nov 1997) |
| antigen-binding site | <immunology> In immune network theory, an idiotope, an antigenic site of an antibody that is responsible for that antibody binding to an antigenic determinant (epitope). Also used of the site on a ligand molecule to which a cell surface receptor binds. (18 Nov 1997) |
| antigen-combining site | See: paratope. (05 Mar 2000) |
| apurinic site | <molecular biology> Sites in DNA from which purines have been lost by cleavage of the deoxy ribose N glycosidic linkage. (18 Nov 1997) |
| apyrimidinic site | <molecular biology> A site on DNA where a base is missing, in this case a pyrimidine (either cytosine or thymine), but the phosphodiester backbone is still intact. Compare: apurinic site. (09 Oct 1997) |