GSBS Student Publications

Title

mRNA poly(A) tail, a 3' enhancer of translational initiation

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Molecular Genetics and Microbiology

Date

7-1-1990

Document Type

Article

Medical Subject Headings

Animals; Base Sequence; Binding, Competitive; Cell-Free System; Genetic Vectors; Globins; Kinetics; Molecular Sequence Data; Peptide Chain Elongation, Translational; *Peptide Chain Initiation, Translational; Plasmids; Poly A; *Protein Biosynthesis; RNA Caps; RNA, Messenger; Rabbits; Reticulocytes; Templates, Genetic; Transcription, Genetic

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

To evaluate the hypothesis that the 3' poly(A) tract of mRNA plays a role in translational initiation, we constructed derivatives of pSP65 which direct the in vitro synthesis of mRNAs with different poly(A) tail lengths and compared, in reticulocyte extracts, the relative efficiencies with which such mRNAs were translated, degraded, recruited into polysomes, and assembled into messenger ribonucleoproteins or intermediates in the translational initiation pathway. Relative to mRNAs which were polyadenylated, we found that nonpolyadenylated [poly(A)-]mRNAs had a reduced translational capacity which was not due to an increase in their decay rates, but was attributable to a reduction in their efficiency of recruitment into polysomes. The defect in poly(A)- mRNAs affected a late step in translational initiation, was distinct from the phenotype associated with cap-deficient mRNAs, and resulted in a reduced ability to form 80S initiation complexes. Moreover, poly(A) added in trans inhibited translation from capped polyadenylated mRNAs but stimulated translation from capped poly(A)- mRNAs. We suggest that the presence of a 3' poly(A) tail may facilitate the binding of an initiation factor or ribosomal subunit at the mRNA 5' end.

Rights and Permissions

Citation: Mol Cell Biol. 1990 Jul;10(7):3441-55.

Related Resources

Link to article in PubMed

Journal Title

Molecular and cellular biology

PubMed ID

1972543