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Deviation from the universal code shown by the gene for surface protein 51A in Paramecium
Nature
|March 14, 1985
Summary
Paramecium immobilization antigens (i-antigens) utilize TAA and TAG codons for amino acid synthesis, not as stop signals. This unique genetic code deviates from all other known organisms.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Paramecium immobilization antigens (i-antigens) are large cell surface proteins.
- Each i-antigen is encoded by a distinct gene, with only one expressed at a time.
- Genes, mRNAs, and proteins for i-antigens are isolatable.
Purpose of the Study:
- To determine the nucleotide sequence of regions of the Paramecium tetraurelia A i-antigen gene.
- To investigate the genetic code utilized by Paramecium.
Main Methods:
- DNA sequencing of the A i-antigen gene from Paramecium tetraurelia stock 51.
Main Results:
- Analysis revealed TAA and TAG stop codons in all reading frames of the A i-antigen gene.
- Despite the presence of stop codons, evidence suggests one reading frame encodes the i-antigen.
Conclusions:
- Paramecium tetraurelia appears to use UAA and UAG codons to code for amino acids.
- This represents a significant deviation from the standard genetic code observed in all other organisms.
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