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. 1976 Aug;73(8):2584–2588. doi: 10.1073/pnas.73.8.2584

Purification and characterization of two initiation factors required for maximal activity of a highly fractionated globin mRNA translation system.

B Safer, S L Adams, W M Kemper, K W Berry, M Lloyd, W C Merrick
PMCID: PMC430692  PMID: 1066667

Abstract

Two additional initiation factors (IF-M4 and IF-M5) have been purified and characterized both physically and biologically. IF-M4 is active as a single polypeptide chain with a molecular weight of 48,000. In contrast, IF-M5 is active as a complex with a molecular weight of about 500,000 and consists of seven major and several minor polypeptide components. Analysis of IF-M5 in two polyacrylamide gel electrophoresis systems indicated that one of the major polypeptide chains of IF-M5 was the 35,000 dalton subunit of IF-MP. This analysis also revealed that IF-M2A, IF-M3, and elongation factor 2 were present as minor components. Both IF-M4 and IF-M5 are required to achieve maximal activity in an assay system dependent on exogenous globin mRNA, but neither factor has been observed to stimulate model reactions that utilize artificial templates [poly(U) or AUG].

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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