Document Type
Article
Publication Date
1-1-1997
Publication Title
Molecular Biology of the Cell
Volume
8
Issue Number
8
First Page
1559
Last Page
1573
DOI
10.1091/mbc.8.8.1559
Disciplines
Biochemistry | Other Chemistry
Abstract
Folding of newly synthesized proteins in vivo is believed to be facilitated by the cooperative interaction of a defined group of proteins known as molecular chaperones. We investigated the direct interaction of chaperones with nascent polypeptides in the cytosol of mammalian cells by multiple methods. A new approach using a polyclonal antibody to puromycin allowed us to tag and capture a population of truncated nascent polypeptides with no bias as to the identity of the bound chaperones. In addition, antibodies that recognize the cytosolic chaperones hsp70, CCT (TRiC), hsp40, p48 (Hip), and hsp90 were compared on the basis of their ability to coprecipitate nascent polypeptides, both before and after chemical cross-linking. By all three approaches, hsp70 was found to be the predominant chaperone bound to nascent polypeptides. The interaction between hsp70 and nascent polypeptides is apparently dynamic under physiological conditions but can be stabilized by depletion of ATP or by cross-linking. The cytosolic chaperonin CCT was found to bind primarily to full-length, newly synthesized actin, and tubulin. We demonstrate and caution that nascent polypeptides have a propensity for binding many proteins nonspecifically in cell lysates. Although current models of protein folding in vivo have described additional components in contact with nascent polypeptides, our data indicate that the hsp70 and, perhaps, the hsp90 families are the predominant classes of molecular chaperones that interact with the general population of cytosolic nascent polypeptides.
Recommended Citation
Daryl K. Eggers, W. J. Welch, and W. J. Hansen. "Complexes Between Nascent Polypeptides and Their Molecular Chaperones In the Cytosol of Mammalian Cells" Molecular Biology of the Cell (1997): 1559-1573. https://doi.org/10.1091/mbc.8.8.1559
Comments
This article is licensed under Creative Commons–Noncommercial–Share Alike 3.0 Unported.The publisher's version of the article can be found online at Molecular Biology of the Cell.