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B Redfield

Publications and source records attributed to B Redfield.

At least 37 records · Page 2Linked to original sources
PubMed1978

Binding of reticulocyte elongation factor 1 to ribosomes and nucleic acids.

The present study has examined the requirements for the binding of rabbit reticulocyte elongation factor 1 (EF-1) to ribosomes under different assay conditions. When a centrifugation procedure was used to separate the ribosome EF-1 complex, the binding of EF-1 to ribosomes required GTP and Phe-tRNA, but not poly(U). The results suggested that undr these conditions a ternary complex, EF-1 . GTP . aminoacyl-tRNA, is necessary for the formation of a ribosome . EF-1 complex. However, when gel filtration was used to isolate the ribosome . EF-1 complex, only template and tRNA were required. These studie emphasize the fact that the procedure used to isolate the ribosome . EF-1 complex determines the requirements for stable complex formation. EF-1 can also interact with nucleic acids such as 28 S and 18 S rRNA, messenger RNA and DNA. In contrast to the binding to ribosomes, EF-1 binding to nucleic acids requires only Mg2+.

Animals↗
PubMed1977

DNA-directed in vitro synthesis of beta-galactosidase. Studies with purified factors.

The phage DNA-directed synthesis of beta-galactosidase has been examined in a system containing the following purified Escherichia coli factors: RNA polymerase; cyclic AMP receptor protein; N10-formyltetrahydrofolate Met-tRNAf transformylase; initiation factors 1, 2, and 3; elongation factors Tu, Ts, and G; release factors 1 and 2; 20 aminoacyl-tRNA synthetases; L factor (Kung, H. F., Spears, C., and Weissbach, H. (1974) J. Biol. Chem. 250, 1556-1562); and Lalpha (Kung, H.-F., Spears, C., and Weissbach, H. (1976) Fed. proc. 35, 1537). Under these conditions, beta-galactosidase synthesis occurs at less than 1% of the rate obtained with unfractionated extracts, which suggested that other required components were lacking. The difficulty in obtaining large amounts of the purified aminoacyl-tRNA synthetases for these studies made it necessary to modify the system. It was possible to conserve many of the purified aminoacyl-tRNA synthetases since at least 13 of them could be replaced by an Ehrlich ascites extract. The ascites extract plus other E. coli purified factors was used as a basic system to search for additional components required for beta-galactosidase synthesis. The present report describes the purification from E. coli extracts of three fractions, called Lbeta, Lgamma, and Ldelta, that are needed to restore enzyme synthesis.

Amino Acyl-tRNA Synthetases↗
PubMed1976

Elongation factor 1 from Artemia salina: properties and disaggregation of the enzyme.

Elongation factor 1 has been purified from undeveloped embryos of Artemia salina. The purified enzyme appears to be an aggregate (molecular weight approximately to 200 000) which on sodium dodecylsulfate gels shows the presence of two major protein bands whose estimated molecular weights are 52 000 and 47 000. Lipid material appears to be associated with the purified protein. In aminoacyl-tRNA binding to ribosomes, there is only a limited turnover of the enzyme, but the protein acts catalytically in amino acid polymerization. The enzyme is disaggregated by a partially purified phospholipase C preparation, elastase and under certain conditions, by guanosine nucleotides. The significance of these results is discussed with respect to the overall role of elongation faction 1 in aminoacyl-tRNA binding to ribosomes.

Amino Acids↗
PubMed1974

Role of phospholipids in the multiple forms of mammalian elongation factor 1.

Evidence is presented that high-molecular-weight aggregates of elongation factor 1 from calf brain and liver contain phospholipids. Sucrose gradient analysis has shown that these high-molecular-weight species can be converted to a low-molecular-weight form after incubation with different phospholipase preparations. In addition, a partially purified elongation factor 1 from rabbit reticulocytes is also converted to a low-molecular-weight species by phospholipase treatment. These data indicate that phospholipids are involved in maintaining the integrity of the high-molecular-weight species and support the view that this species is an aggregate of the low-molecular-weight elongation factor 1.

Animals↗
PubMed1973

Multiple forms of elongation factor 1 from calf brain.

Heavy and light forms of elongation factor 1 (EF-1) from calf brain have been partially purified. The heterogeneous heavy species (EF-1(H)) with molecular weights of 2.5 x 10(5) to over 1 x 10(6) appears to be a complex or aggregate of the light form of the enzyme (EF-1(L)); the latter has a molecular weight of between 50,000 and 60,000. EF-1(H) but not EF-1(L), contains significant amounts of free and esterified cholesterol. Although EF-1(H) and EF-1(L) are both active in aminoacyl-tRNA binding to ribosomes, EF-1(L) reacts with GTP and aminoacyl-tRNA more efficiently than EF-1(H).

Ammonium Sulfate↗
PubMed1972

Interaction of eukaryote elongation factor EF 1 with guanosine nucleotides and aminoacyl-tRNA.

Evidence for two species of elongation factor 1 (EF 1(A) and EF 1(B)) from calf brain has been obtained by molecular sieve chromatography on Sephadex G-150. A high molecular weight form, EF 1(A), interacts with GTP to form an EF 1(A)-GTP complex. GDP also reacts with EF 1, but unlike the reaction with GTP, an EF 1(B)-GDP complex is formed that contains a lower molecular weight and labile species of EF 1. The results also indicate that EF 1(A)-GTP reacts with aminoacyl-tRNA to form an aminoacyl-tRNA-EF 1(B)-GTP complex. These results are discussed with regard to the role of EF 1 in aminoacyl-tRNA binding to ribosomes.

Animals↗