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Effect of upstream reading frames on translation efficiency in simian virus 40 recombinants
Molecular and Cellular Biology
|July 1, 1986
Summary
Mammalian ribosomes can restart translation internally. Efficient expression of mouse dihydrofolate reductase (DHFR) from recombinant viruses depends on the proximity of upstream reading frame terminators to the DHFR initiation codon.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Previous studies demonstrated efficient mouse dihydrofolate reductase (DHFR) expression from simian virus 40 (SV40) recombinant viruses.
- Expression occurred even when the DHFR coding sequence was downstream from other initiation codons (AUGs) in the viral mRNA.
Purpose of the Study:
- To investigate internal translation initiation in mammalian cells.
- To determine the role of upstream reading frame termination in DHFR expression from SV40 recombinants.
Main Methods:
- Construction of a series of SVGT7dhfr recombinant viruses with varied termination codon positions.
- Infection of CV1 cells with recombinant viruses.
- Analysis of DHFR production in infected cells.
Main Results:
- Efficient DHFR production required terminators of the upstream VP2-VP3 reading frame to be positioned near the DHFR initiation codon.
- The proximity of termination codons influenced DHFR expression levels.
Conclusions:
- Mammalian ribosomes possess the capability for translational reinitiation.
- The positioning of upstream translation termination signals is crucial for efficient internal translation initiation.