amiloride-sensitive sodium channel

A sodium channel important in the detection of the taste of salt. Such channels are inhibited by amiloride, which also mutes the taste of salt.

Ames test

A simple, rapid means of detecting carcinogens by measuring a chemical's ability to induce mutations in Salmonella bacteria.

Amanitin

A cyclic octapeptide from the mushroom Amanita phalloides (the destroying angel) that is a potent inhibitor of the elongation phase of RNA synthesis catalyzed by RNA polymerase II.

alternative splicing

The generation of unique but related mRNA molecules by the differential splicing of the pre-mRNA transcript. By allowing the synthesis of more than one mRNA molecule from a premRNA transcript, alternative splicing increases the encoding potential of the genome.

α-ketoglutarate dehydrogenase

A citric acid cycle enzyme that catalyzes the oxidative decarboxylation of α-ketoglutarate to yield succinyl CoA. This enzyme, which helps to regulate the rate of the citric acid cycle, is structurally and mechanistically similar to the pyruvate dehydrogenase complex

α helix

common structural motif in proteins, in which a polypeptide main chain forms the inner part of a right-handed helix, with the side chains extending outward; the helix is stabilized by intrachain hydrogen bonds between NH and CO groups of the main chain.

allosteric interaction

An interaction between a small molecule (a ligand) and a site on a protein that may be some distance away from the active site; the interaction causes a conformational change and consequent alteration in the catalytic activity of the protein.