+ Translate

Regulation of initiation factors during translational repression caused by serum depletion. Abundance, synthesis, and turnover rates

, : Regulation of initiation factors during translational repression caused by serum depletion. Abundance, synthesis, and turnover rates. Journal of Biological Chemistry 260(9): 5486-5492

During growth in unreplenished medium, the fraction of active, polysomal ribosomes progressively decreases .apprx. 3-fold from 80-90% to only 20-40% due to a reduced rate of initiation. To assess whether the abundance of initiation factors could be involved in this repression of translational activity, HeLa cell cytoplasmic lysates were resolved by 2-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and spots corresponding to the initiation factor proteins were quantitated. The relative abundance of most of the initiation factor proteins only decreases by 10-40% and roughly parallels that of the ribosomes. Measurement of the rates of synthesis and turnover of the initiation factor proteins establishes that during periods of active growth, synthesis and degradation occur coordinately with total cell protein. As growth rate decreases, the synthesis of some initiation factor proteins, particularly eukaryotic initiation factor (eIF)-3 subunits, becomes depressed. Serum stimulation of serum-depleted cells recruits most inactive ribosomes and mRNA into polysomes, but most initiation factor mRNA are not selectively recruited. The principal exceptions are eIF-3p24 which exhibits 4- to 5-fold enhanced synthesis, and eIF-3p44 and eIF-4A whose syntheses are moderately stimulated.

(PDF 0-2 workdays service)

Accession: 006288740

PMID: 3988764

Submit PDF Full Text: Here

Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:

Related references

Duncan, R.; Hershey, J.W., 1985: Regulation of initiation factors during translational repression caused by serum depletion. Covalent modification. One to 2 h after transfer of HeLa cells into fresh serum-containing medium, when translation rates are maximal, the initiation factor proteins were examined on immunoblots of two-dimensional gels. Eukaryotic initiation factor (eIF)-2 alpha, eIF-2...

Clifford, R.J.; Kaplan, J.H., 2009: Regulation of Na,K-ATPase subunit abundance by translational repression. The Na,K-ATPase is an alphabeta heterodimer responsible for maintaining fluid and electrolyte homeostasis in mammalian cells. We engineered Madin-Darby canine kidney cell lines expressing alpha(1)FLAG, beta(1)FLAG, or beta(2)MYC subunits via a tet...

Clayton, R.M.; Truman, D.E.; Hannah, A.I., 1974: RNA turnover and translational regulation of specific crystallin synthesis. A method is described for estimating both the turnover of RNA associated with polysomes involved in specific protein synthesis and the rate of synthesis of polypeptides in relation to the total amount of specifically engaged polysomal RNA. The rat...

Ivester, C.T.; Tuxworth, W.J.; Cooper, G.; McDermott, P.J., 1995: Contraction accelerates myosin heavy chain synthesis rates in adult cardiocytes by an increase in the rate of translational initiation. The purpose of this study was to determine the mechanism by which contraction acutely accelerates the synthesis rate of the contractile protein myosin heavy chain (MHC). Laminin-adherent adult feline cardiocytes were maintained in a serum-free med...

Chin, K.V.; Cade, C.; Brostrom, C.O.; Galuska, E.M.; Brostrom, M.A., 1987: Calcium-dependent regulation of protein synthesis at translational initiation in eukaryotic cells. Evidence that Ca2+ may serve as a physiologic regulator of post-transcriptional protein synthesis was recently reported (Brostrom, C. O., Bocckino, S. B., Brostrom, M. A., and Galuska, E. M. (1986) Mol. Pharmacol. 29, 104-111). To evaluate further...

Gallie, D.R., 2007: Use of in vitro translation extract depleted in specific initiation factors for the investigation of translational regulation. Regulation of gene expression often involves the control of translation mediated through one or more initiation factors that are required for the translation of eukaryotic mRNAs. Genetic and molecular biological approaches can be highly useful in...

Xiong, W.; Xie, Q.; Hsieh, C.C.; Papaconstantinou, J., 1997: Regulation of C/EBPbeta isoform synthesis in LPS-treated mouse livers by alternative translational initiation. Molecular Biology of the Cell 8(SUPPL ): 434A, Nov

Yoshida, M., 1973: Inhibition of protein synthesis at the translational level--selective translation and initiation factors. Tanpakushitsu Kakusan Koso. Protein, Nucleic Acid, Enzyme 18(1): 53-61

Abid, M.R.; Li, Y.; Anthony, C.; D.B.nedetti, A., 1999: Translational regulation of ribonucleotide reductase by eukaryotic initiation factor 4E links protein synthesis to the control of DNA replication. Ribonucleotide reductase synthesizes dNDPs, a specific and limiting step in DNA synthesis, and can participate in neoplastic transformation when overexpressed. The small subunit (ribonucleotide reductase 2 (RNR2)) was cloned as a major product in...

Rabinovitz, M., 1974: Translational repression in the control of globin chain initiation by hemin. Annals of the New York Academy of Sciences 241(0): 322-333