Chaperone (protein)

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A top-view of a bacterial chaperone complex. This is a chapronin (HSP60) called GroEL.

A molecular chaperone is a protein which does things to other proteins. They are mostly concerned with protein folding.[1][2] [3][4][5][6]

Some help assemble or take apart other macromolecular structures. They do not occur in these structures when the structures go about their normal functions. What they do is:

  • Fold over half of all mammalian proteins.
  • Unfold proteins.
  • Assemble proteins.
  • Disassemble proteins.

The first protein to be called a chaperone assists the assembly of nucleosomes from folded histones and DNA.[7] Those assembly chaperones, especially in the nucleus, assemble folded subunits into larger structures such as cell organelles.[8]

One major function of chaperones is to prevent polypeptide chains and subunits sticking together in clumps which do not function. Some chaperones are "holdases" which act to stop aggregation. Others, called "foldases", do help fold proteins which cannot do it themselves. Such proteins violate Anfinsen's dogma, which said protein folding was automatic.[9]

References[change | change source]

  1. Richardson RT, Alekseev OM, Grossman G, Widgren EE, Thresher R, Wagner EJ, et al. (2006). "Nuclear autoantigenic sperm protein (NASP), a linker histone chaperone that is required for cell proliferation". The Journal of Biological Chemistry. 281 (30): 21526–34. doi:10.1074/jbc.M603816200. PMID 16728391.
  2. Alekseev OM, Richardson RT, Alekseev O, O'Rand MG (2009). "Analysis of gene expression profiles in HeLa cells in response to overexpression or siRNA-mediated depletion of NASP". Reproductive Biology and Endocrinology. 7: 45. doi:10.1186/1477-7827-7-45. PMC 2686705. PMID 19439102.
  3. Ellis RJ (2006). "Molecular chaperones: assisting assembly in addition to folding". Trends in Biochemical Sciences. 31 (7): 395–401. doi:10.1016/j.tibs.2006.05.001. PMID 16716593.
  4. Hartl F.U. 1996. Molecular chaperones in cellular protein folding. Nature 381, 571–579
  5. Bartlett A.L. & Radford S.E. 2009. An expanding arsenal of experimental methods yields an explosion of insights into protein folding mechanisms. Nat. Struct. Mol. Biol. 16, 582–588
  6. Hartl F.U. & Hayer-Hartl M. 2009. Converging concepts of protein folding in vitro and in vivo. Nature Structural & Molecular Biology 16 (6): 574–581. [1]
  7. Ellis R.J. 1996. Discovery of molecular chaperones. Cell stress chaperones 1 (3): 155–60.
  8. Richardson R.T. et al 2006 (2006). "Nuclear autoantigenic sperm protein (NASP), a linker histone chaperone that is required for cell proliferation". Journal of Biological Chemistry. 281 (30): 21526–34. doi:10.1074/jbc.M603816200. PMID 16728391.
  9. Kris Pauwels et al 2007 (2007). "Chaperoning Anfinsen: the dteric foldases" (PDF). Molecular Microbiology. 64 (4): 917–922. doi:10.1111/j.1365-2958.2007.05718.x. PMID 17501917. S2CID 6435829. Archived from the original (PDF) on 2012-05-23. Retrieved 2013-09-19.