| nonsense codon | <molecular biology> The three codons, UAA (known as ochre), UAG (amber) and UGA (opal), that do not code for an amino acid but act as signals for the termination of protein synthesis. Any mutation that causes a base change which produces a nonsense codon results in premature termination of protein synthesis and probably a nonfunctional or nonsense protein. (13 Nov 1997) |
|---|---|
| initiating codon | The trinucleotide AUG (or sometimes GUG) that codes for the first amino acid in protein sequences, formylmethionine; the latter is often removed post-transcriptionally. Synonym: start codon. (05 Mar 2000) |
| initiation codon | The codon 5' AUG in mRNA, at which polypeptide synthesis is started. It is recognised by formylmethionyl tRNA in bacteria and by methionyl tRNA in eukaryotes. (18 Nov 1997) |
| ochre codon | The codon UAA, one of the three that causes termination of protein synthesis. The most frequent termination codon in E. Coli genes. (18 Nov 1997) |
| opal codon | <molecular biology> The codon UGA, one of the three that causes termination of protein synthesis. (18 Nov 1997) |
| termination codon | <molecular biology> The three codons, UAA known as ochre, UAG as amber and UGA as opal, that do not code for an amino acid but act as signals for the termination of protein synthesis. They are not represented by any tRNA and termination is catalysed by protein release factors. There are two release factors in E. Coli, RF1 recognises UAA and UAG, RF2 recognises UAA and UGA. Eukaryotes have a single GTP requiring factor, eRF. See: ochre suppressor, amber suppressor. (13 Jan 1998) |
| umber codon | The termination codon UGA. Synonym: opal codon. (05 Mar 2000) |