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↗

PubMed1972

Initiation of protein synthesis in HeLa cells.

Initiation of protein synthesis in HeLa cells has been synchronized by exposure of the cells to fluoride. Double-labeling of such cells for short pulses with [(35)S]methionine and a tritiated amino acid, followed by Edman degradation of the puromycin-released nascent peptides, has shown that the percent of N-terminal methionine incorporated compared to total incorporation is significantly higher than the value obtained with any of the other amino acids tested. The results suggest that the bulk of the nascent proteins synthesized in vivo by HeLa cells are initiated with methionine.

Amino Acids↗

PubMed1972

The effect of various nucleotides on the helical nature of a ribosomal protein(s) from Escherichia coli.

In the presence of GTP or GDP, there is a decrease in the circular dichroic absorption of ribosomal proteins L(7) and L(12) at 221-222 nm, suggesting that these nucleotides influence the helical content of these proteins.

Adenosine Triphosphate↗

PubMed1972

In vitro synthesis of procollagen on polysomes.

The major collagenous products synthesized in a cell-free polysome preparation are pro-alpha1 and pro-alpha2, formed in a ratio of 2:1. They are the precursor forms of alpha1 and alpha2 chains of normal connective-tissue collagen that are also formed in small amounts. A procollagen peptidase activity has been demonstrated in the supernatant fraction that can account for the formation of alpha1 and alpha2 chains from their precursors. The polysomal system is activated by a salt extract of reticulocyte ribosomes and is inhibited by aurintricarboxylic acid, suggesting that the polysomes are able to initiate protein synthesis.

Animals↗

PubMed1971