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Protein Synthesis In Rabbit Reticulocytes: Mechanism Of Protein Synthesis Inhibition By Heme-Regulated Inhibitor, A. Das, O. Ralston, M. Grace, R. Roy, P. Ghosh-Dastidar, H. K. Das, B. Yaghmai, S. Palmieri, N. K. Gupta
Protein Synthesis In Rabbit Reticulocytes: Mechanism Of Protein Synthesis Inhibition By Heme-Regulated Inhibitor, A. Das, O. Ralston, M. Grace, R. Roy, P. Ghosh-Dastidar, H. K. Das, B. Yaghmai, S. Palmieri, N. K. Gupta
Chemistry Department: Faculty Publications
Partially purified Met-tRNAf binding factor, eIF-2, was phosphorylated by using heme-regulated inhibitor (HRI). Phosphorylated eIF-2 was freed from HRI by phosphocellulose column chromatography. Analysis by isoelectric focusing showed 100% phosphorylation of the 38,000-dalton subunit of eIF-2. Both eIF-2 and eIF-2(P) formed ternary complexes with Met-tRNAf and GTP with almost the same efficiency, and in both cases the ternary complex formation was drastically inhibited by prior addition of Mg2+. However, whereas the ternary complexes formed with eIF-2 could be stimulated by Co-eIF-2C at 1 mM Mg2+ and dissociated by Co-eIF-2B at 5 mM Mg2+, …
Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Postribosomal Supernatant Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates And Inhibition Of Ternary Complex (Met-TrnaFMet•Eif-2•Gtp) Formation By Heme-Regulated Inhibitor, R. O. Ralston, A. Das, M. Grace, H. Das, N. K. Gupta
Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Postribosomal Supernatant Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates And Inhibition Of Ternary Complex (Met-TrnaFMet•Eif-2•Gtp) Formation By Heme-Regulated Inhibitor, R. O. Ralston, A. Das, M. Grace, H. Das, N. K. Gupta
Chemistry Department: Faculty Publications
During heme deficiency in reticulocyte lysates, a translational inhibitor (heme-regulated inhibitor, HRI) that blocks polypeptide chain initiation is activated. HRI is a protein kinase that specifically phosphorylates the 38,000-dalton subunit of the Met-tRNAfMet binding factor, eIF-2. Phosphorylation of eIF-2 by HRI prevents its interaction with at least two additional factors, resulting in a net reduction in formation of ternary complex (Met-tRNAfMet eIF-2•GTP) and AUG-dependent transfer of Met-tRNAfMet to 40S ribosomal subunits. A factor (sRF) that reverses protein synthesis inhibition in heme-deficient Iysates has been purified from reticulocyte postribosomal supernatant. sRF also reverses the inhibition …
Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Ribosomal Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates, R. O. Ralston, A. Das, A. Dasgupta, R. Roy, S. Palmieri, N. K. Gupta
Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Ribosomal Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates, R. O. Ralston, A. Das, A. Dasgupta, R. Roy, S. Palmieri, N. K. Gupta
Chemistry Department: Faculty Publications
A ribosomal salt (0.5 M KCI) wash factor (RF) that reverses inhibition of protein synthesis in heme-deficient reticulocyte lysates has been resolved from the bulk of Met-tRNAtmet- binding factor (EIF-1), Co-EIF-I, and EIF-2 (ternary complex dissociation factor, TDF). The purified RF restores protein synthesis activity of heme-deficient lysates to the level observed in the presence of hemin. No direct correlation exists between amount of EIF-i activity and ability to reverse inhibition of protein synthesis in heme-deficient lysates. Homogeneous preparations of EIF-i are completely inactive in reversal of protein synthesis inhibition in heme-deficient lysates. These findings suggest that …