On the Nature of Allosteric Transitions: A Plausible Model

The penicillin method (Davis, 1948; Lederberg and Zinder, 1948) has permitted convenient isolation of auxotrophicl mutants of Escherichia coli with specific growth requirements for most of the known water-soluble vitamins, as well as amino acids, purines, and pyrimidines. Accordingly, when crystalline vitamin B12 became available, a search was made for mutants requiring this nutrilite. Several strains of the desired type were promptly recovered. In all cases methionine, but not homocysteine, could be substituted for the vitamin. This paper describes certain biochemical properties of these mutants, as well as of others responding to methionine but not to B,2.

Mutants of escherichia coli requiring methionine or vitamin b12

▪ Abstract Eukaryotic translation initiation factor 4F (eIF4F) is a protein complex that mediates recruitment of ribosomes to mRNA. This event is the rate-limiting step for translation under most circumstances and a primary target for translational control. Functions of the constituent proteins of eIF4F include recognition of the mRNA 5′ cap structure (eIF4E), delivery of an RNA helicase to the 5′ region (eIF4A), bridging of the mRNA and the ribosome (eIF4G), and circularization of the mRNA via interaction with poly(A)-binding protein (eIF4G). eIF4 activity is regulated by transcription, phosphorylation, inhibitory proteins, and proteolytic cleavage. Extracellular stimuli evoke changes in phosphorylation that influence eIF4F activity, especially through the phosphoinositide 3-kinase (PI3K) and Ras signaling pathways. Viral infection and cellular stresses also affect eIF4F function. The recent determination of the structure of eIF4E at atomic resolution has provided insight about how translation is initiat...

eIF4 Initiation Factors: Effectors of mRNA Recruitment to Ribosomes and Regulators of Translation

https://mmbr.asm.org/content/mmbr/47/1/1.full.pdf

Comparison of initiation of protein synthesis in procaryotes, eucaryotes, and organelles.

https://www.jbc.org/content/264/14/8222.full.pdf

Cloning, structure, and expression of the mitochondrial cytochrome P-450 sterol 26-hydroxylase, a bile acid biosynthetic enzyme.

Radiolabeling of proteins by reductive alkylation with [14C]formaldehyde and sodium cyanoborohydride

Glutamyl and glutaminyl ribonucleic acid synthetases of escherichia coli w. separation, properties, and stimulation of adenosine triphosphate-pyrophosphate exchange by acceptor ribonucleic acid.

Synthetic and Degradative Investigations of the Structure of Folinic Acid-SF

The 5' and 3' untranslated regions of satellite tobacco necrosis virus RNA affect translational efficiency and dependence on a 5' cap structure.

Publisher Summary This chapter describes the procedures for obtaining highly purified eukaryotic initiation factors (eIF) eIF-2, eIF-3, eIF-4A, eIF-4B, eIF-4F, partially purified eIF-5, and highly purified elongation factors (EF) EF-Iα, EF-Iβγ, and EF-2 from wheat germ. Initiation of the translation of messenger RNA (mRNA) on cytoplasmic ribosomes of eukaryotic cells is a complicated process requiring Met-transfer RNA (tRNA), Guanosine-5'-triphosphate (GTP), Adenosine-5'-triphosphate (ATP), 10 initiation factors, and one or more ancillary factors. The chapter also describes some of the physical and functional properties of these factors. It also outlines the assay for elongation factors, EF-Iα, EF-Iβγ, and EF-2 and the assay for initiation factors, eIF-3, eIF-4A, eIF-4B, eIF-4F, and eIF-5. The elongation factors are measured by their ability to support poly (U)-directed polyphenylalanine synthesis.

Joanne M. Ravel

Papers

Radiolabeling of proteins by reductive alkylation with [14C]formaldehyde and sodium cyanoborohydride

Glutamyl and glutaminyl ribonucleic acid synthetases of escherichia coli w. separation, properties, and stimulation of adenosine triphosphate-pyrophosphate exchange by acceptor ribonucleic acid.

Synthetic and Degradative Investigations of the Structure of Folinic Acid-SF

The 5' and 3' untranslated regions of satellite tobacco necrosis virus RNA affect translational efficiency and dependence on a 5' cap structure.

Purification and properties of protein synthesis initiation and elongation factors from wheat germ.