Mode of action of the hemin-controlled inhibitor of protein synthesis

de Haro, C. ; Datta, A. ; Ochoa, Severo (1978) Mode of action of the hemin-controlled inhibitor of protein synthesis Proceedings of the National Academy of Sciences of the United States of America, 75 (1). pp. 243-247. ISSN 0027-8424

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Despite the finding that the hemin-controlled translational inhibitor in reticulocyte lysates is a cyclic AMP-independent protein kinase that phosphorylates the small subunit of the initiation factor eIF-2, the mechanism of inhibition of translation remained unexplained. Whereas treatment of hemin-containing lysates with inhibitor in the presence of ATP inhibited translation, the same treatment of highly purified eIF-2 did not affect its ability to form a ternary complex with initiator Met-tRNA and GTP or a 40S initiation complex. We have isolated from ribosomal salt washes a protein (eIF-2 stimulating protein) that enhances the capacity of unphosphorylated eIF-2 to form ternary or 40S initiation complexes but has no effect on the phosphorylated factor. At low concentrations, eIF-2 is virtually inactive without this stimulating protein. Therefore, the translational inhibitor acts by converting eIF-2 to a form that is not stimulated by the stimulating protein.

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ID Code:9323
Deposited On:02 Nov 2010 12:29
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