Determination of the amounts of the protein synthesis initiation and elongation factors in wheat germ

• Published in: The Journal of biological chemistry 1990-10, Vol.265 (29), p.17967-17973
• Main Authors: Browning, K S, Humphreys, J, Hobbs, W, Smith, G B, Ravel, J M
• Format: Article
• Language: English
• Subjects: Antibodies - isolation & purification; ARN MENSAJERO; ARN MESSAGER; Biological and medical sciences; BLE; CEREAL GERMS; elongation factors; Enzyme-Linked Immunosorbent Assay; EXTRACTOS; EXTRACTS; EXTRAIT; Fundamental and applied biological sciences. Psychology; GERME DE CEREALE; GERMENES DE CEREALES; Immunoblotting; initiation factors; MESSENGER RNA; Molecular and cellular biology; Molecular genetics; Molecular Weight; Peptide Elongation Factors - analysis; Peptide Elongation Factors - immunology; Peptide Initiation Factors - analysis; Peptide Initiation Factors - immunology; PROTEIN SYNTHESIS; RIBOSOMAS; RIBOSOME; RIBOSOMES; Ribosomes - chemistry; Seeds - metabolism; SINTESIS DE PROTEINAS; SYNTHESE PROTEIQUE; TRANSLATION; Translation. Translation factors. Protein processing; TRIGO; Triticum - metabolism; wheat germ; WHEATS
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)38258-9

Previous work by Browning et al. (Browning, K. S., Lax, S. R., Humphreys, J., Ravel, J. M., Jobling, S. A., and Gehrke, L. (1988) J. Biol. Chem. 263, 9630-9634) indicated that wheat germ extracts do not contain sufficient amounts of some of the protein synthesis initiation factors to obtain optimal translation of all mRNAs. In this investigation, a quantitative enzyme-linked immunosorbent assay was used to determine the amounts of eukaryotic initiation factors (eIF) 2, 3, 4A, 4F, and (iso)4F as well as the amounts of 40 S ribosomal subunits and elongation factors (EF) 1 alpha and 2 present in wheat germ extracts. EF-1 alpha is present in the highest amount (approximately 5% of the total protein), and eIF-4F is present in the lowest amount (approximately 0.03% of the total protein). The micromolar amounts of the factors and ribosomes are as follows: EF-1 alpha, 34; EF-2, 5.2; eIF-2, 1.5; eIF-3, 0.7; eIF-4A, 3.0, eIF-4F, 0.09; eIF-(iso)4F, 0.8; and 40 S ribosomal subunits, 3.2. The molar ratios of the factors to 40 S ribosomal subunits are approximately 11:1 for EF-1 alpha, 1.6:1 for EF-2, 0.45:1 for eIF-2, 0.2:1 for eIF-3, 0.9:1 for eIF-4A, 0.03:1 for eIF-4F, and 0.25:1 for eIF-(iso)4F. These findings strongly suggest that the concentrations of the initiation factors, particularly those factors required for the binding of mRNA to ribosomes, may play a major role in regulating the translation of mRNAs within the cell.