Related Experiment Video
Updated: Jul 16, 2026
10:59
Production of Apolipoprotein C-III Knockout Rabbits using Zinc Finger Nucleases
Published on: November 18, 2013
A UGA termination suppression tRNATrp active in rabbit reticulocytes
Nature
|January 3, 1980
Summary
Researchers identified a transfer RNA for tryptophan (tRNATrp) in rabbit cells that can read through the UGA stop codon in beta-haemoglobin messenger RNA. This readthrough produces functional proteins, highlighting a natural mechanism for expanding the proteome beyond standard stop codons.
Area of Science:
- Molecular Biology
- Genetics
- Protein Synthesis
Background:
- Gene expression relies on accurate translation of messenger RNA (mRNA) sequences.
- Termination codons (UAA, UAG, UGA) signal the end of protein synthesis.
- Variations in translation can lead to non-canonical protein products.
Purpose of the Study:
- To investigate the role of specific transfer RNAs (tRNAs) in translational readthrough.
- To identify mechanisms that suppress termination codons during protein synthesis.
- To determine if readthrough products of beta-haemoglobin mRNA have biological significance.
Main Methods:
- Purification of transfer RNA for tryptophan (tRNATrp) from rabbit reticulocytes.
- In vitro translation assays using beta-haemoglobin mRNA.
- Analysis of protein products in reticulocyte lysates and intact cells.
Main Results:
- A specific tRNATrp was isolated that suppresses the UGA termination codon of beta-haemoglobin mRNA.
- Evidence confirmed the presence of beta-haemoglobin readthrough protein in both cell-free translation systems and intact rabbit cells.
- The study demonstrated that UGA and UAG, but not UAA, termination codons can be suppressed by natural readthrough mechanisms.
Conclusions:
- A specific tRNATrp facilitates readthrough of the UGA stop codon in beta-haemoglobin mRNA.
- Readthrough proteins, generated by suppressing specific termination codons, can be functional and essential.
- This mechanism expands the functional proteome and provides insights into translational regulation.
Related Concept Videos
01:39Epistasis
In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...
01:44Termination of Translation
The large ribosomal subunit has several important structures essential to translation. These include the peptidyl transferase center (PTC) - which is the site where the peptide bond is formed - and a large, internal, water-filled tube through which the nascent polypeptide moves. This latter structure is called the Peptide Exit Tunnel, and it begins at the PTC and spans the body of the large ribosomal subunit. During translation, as the nascent polypeptide chain is synthesized, it passes through...
02:42Transcription Attenuation in Prokaryotes
Transcriptional attenuation occurs when RNA transcription is prematurely terminated due to the formation of a terminator mRNA hairpin structure. Bacteria use these hairpins to regulate the transcription process and control the synthesis of several amino acids including histidine, lysine, threonine, and phenylalanine. Transcription attenuation takes place in the non-coding regions of mRNA.
There are several different mechanisms used to attenuate transcription. In ribosome mediated...
There are several different mechanisms used to attenuate transcription. In ribosome mediated...
01:14Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...