UGA is translated as cysteine in pheromone 3 of Euplotes octocarinatus.
Pheromone 3 mRNA of the ciliate Euplotes octocarinatus contains three in-frame UGA codons that are translated as cysteines. This was revealed from cDNA sequencing and from plasma desorption mass spectrometry of cleaved pheromone 3 in connection with pyridylethylation of the fragments. N-terminal sequence analysis of carboxymethylated protein confirmed this conclusion for the first of the three UGA codons. Besides UGA the common cysteine codons UGU and UGC are also used to encode cysteine. UAA functions as a termination codon. No UAG codon was found. In connection with results reported for other ciliates, this suggests that the role of the classic termination codons had not yet been established when the ciliates started to diverge from other eukaryotes.
Meyer
F
F
Institute of Zoology, University of Münster, Federal Republic of Germany.
Schmidt
H J
HJ
Plümper
E
E
Hasilik
A
A
Mersmann
G
G
Meyer
H E
HE
Engström
A
A
Heckmann
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016798:Ciliophora / Q000235:genetics* / Q000502:physiology; D003545:Cysteine; D004247:DNA / Q000235:genetics; D005815:Genetic Code; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010443:Peptide Chain Termination, Translational; D010446:Peptide Fragments / Q000737:chemistry; D010675:Pheromones / Q000235:genetics*; D015183:Restriction Mapping
D010446:Peptide Fragments; D010675:Pheromones; D004247:DNA; D003545:Cysteine