Human Mpp11 J protein: ribosome-tethered molecular chaperones are ubiquitous

Science. 2005 May 13;308(5724):1032-4. doi: 10.1126/science.1109247. Epub 2005 Mar 31.


The existence of specialized molecular chaperones that interact directly with ribosomes is well established in microorganisms. Such proteins bind polypeptides exiting the ribosomal tunnel and provide a physical link between translation and protein folding. We report that ribosome-associated molecular chaperones have been maintained throughout eukaryotic evolution, as illustrated by Mpp11, the human ortholog of the yeast ribosome-associated J protein Zuo. When expressed in yeast, Mpp11 partially substituted for Zuo by partnering with the multipurpose Hsp70 Ssa, the homolog of mammalian Hsc70. We propose that in metazoans, ribosome-associated Mpp11 recruits the multifunctional soluble Hsc70 to nascent polypeptide chains as they exit the ribosome.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Amino Acid Substitution
  • Binding Sites
  • Cell Line
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • HSC70 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins / metabolism
  • Humans
  • Molecular Chaperones / chemistry
  • Molecular Chaperones / metabolism*
  • Oncogene Proteins / chemistry
  • Oncogene Proteins / metabolism*
  • Potassium Chloride / pharmacology
  • Protein Structure, Tertiary
  • RNA-Binding Proteins
  • Ribosomes / metabolism*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism


  • DNA-Binding Proteins
  • DNAJC2 protein, human
  • HSC70 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • HSPA8 protein, human
  • Molecular Chaperones
  • Oncogene Proteins
  • RNA-Binding Proteins
  • Saccharomyces cerevisiae Proteins
  • ZUO1 protein, S cerevisiae
  • Adenosine Diphosphate
  • Potassium Chloride