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Protein Science, Vol 1, Issue 8 980-985, Copyright © 1992 by Cold Spring Harbor Laboratory Press
ARTICLE |
C. RYAN, T. H. STEVENS and M. J. SCHLESINGER
Department of Molecular Microbiology, Box 8230, Washington University School of Medicine, St. Louis, Missouri 63110
Several of the major heat shock proteins (HSPs) function normally as molecular chaperones to prevent aggregation of immature polypeptides and thereby facilitate folding and oligomerization. To determine their effect on nascent polypeptides, we added purified preparations of different isoforms of HSP70 to in vitro translation reactions primed by the 26S mRNA of Sindbis virus, which encodes an autoprotease that functions cotranslationally, or by the mRNA encoding the yeast vacuolar H(+)ATPase, which is formed by a novel transpeptidase activity that removes the central region of the initial polypeptide. In the presence of HSP70s both the autoprotease and transpeptidase activities were inhibited, indicating that these chaperones can interact with nascent polypeptides and, in the cases studied here, perturb their normal structures.
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