Protein Quaternary Structure: Subunit–Subunit Interactions

Susan Jones, University College, London, England
Janet M Thornton, University College, London, England

Published online: April 2001

DOI: 10.1038/npg.els.0003120

The quaternary structure of proteins is the highest level of structural organization observed in these macromolecules. The multimeric proteins that result from quaternary structure formation involve the association of protein subunits through hydrophobic and electrostatic interactions. Protein quaternary structure has important implications for protein folding and function.

Keywords: protein–protein interaction; subunit; oligomer; molecular recognition; multimer

Figure 1. Molscript diagrams depicting the secondary structure elements and the quaternary structure of (a) homodimeric interleukin 8; (b) heterodimeric human chorionic gonadotrophin; (c) homodimeric HIV-1 protease; (d) heterotetrameric human haemoglobin. In each diagram the protein subunits are differentiated by colour, and in (d) one -protomer of haemoglobin is coloured red and one green. The haem groups in each subunit shown in (d) are depicted by ball-and-stick representations.
Figure 2. Modes of association in multimeric proteins: (a) isologous, in which the binding sets (indicated by the letters ‘a’ and ‘b’) are identical; (b) heterologous, in which the binding sets (indicated by the letters ‘a’, ‘b’, ‘c’ and ‘d’) are not identical. Adapted from Monod et al., (1965).
Figure 3. The accessible surface area of a protein. The diagram shows just two atoms, with a probe sphere (with a radius of R) defining the accessible surface.
close
 References
    Argos P (1988) An investigation of protein subunit and domain interfaces. Protein Engineering 2: 101–113.
    Bernstein FC, Koetzle TF, Williams GJB et al. (1977) The protein data bank: a computer-based archival file for macromolecular structures. Journal of Molecular Biology 112: 535–542.
    Chothia C and Janin J (1975) Principles of protein–protein recognition. Nature 256: 705–708.
    Fersht AR (1987) The hydrogen bond in molecular recognition. Trends in Biochemical Sciences 12: 301–304.
    Jaenicke R (1987) Folding and association of proteins. Progress in Biophysics and Molecular Biology 29: 117–237.
    Jones S and Thornton JM (1995) Protein–protein interactions: a review of protein dimer structures. Progress in Biophysics and Molecular Biology 63: 31–65.
    Jones S and Thornton JM (1996) Principles of protein–protein interactions. Proceedings of the National Academy of Sciences of the USA 93: 13–20.
    Lapthorn AJ, Harris DC, Littlejohn A et al. (1994) Crystal structure of human chorionic gonadotropin. Nature 369: 455–461.
    Lawrence MC and Colman PM (1993) Shape complementarity at protein/protein interfaces. Journal of Molecular Biology 234: 946–950.
    Lee B and Richards FM (1971) The interpretation of protein structures: estimation of static accessibility. Journal of Molecular Biology 55: 379–400.
    Miller S (1989) The structure of interfaces between subunits of dimeric and tetrameric proteins. Protein Engineering 3: 77–83.
    Miller S, Lesk AM, Janin J and Chothia C (1987) The accessible surface area and stability of oligomeric proteins. Nature 328: 834–836.
    Monod J, Wyman J and Changeux J (1965) On the nature of allosteric transitions: a plausible model. Journal of Molecular Biology 12: 88–118.
    Navia MA, Fitzgerald PMD, McKeever BM et al. (1989) Three-dimensional structure of aspartyl protease from human immunodeficiency virus HIV-1. Nature 337: 615–620.
 Further Reading
    book Banaszak LJ, Birktoft JJ and Barry CD (1981) Protein–protein interactions and protein structures. In: Protein–Protein Interactions, pp. 31–128. New York: Wiley.
    Chan WW (1976) The relationship between quaternary structure and enzyme activity. Trends in Biological Sciences 11: 258–260.
    book Duquerroy S, Cherfils J and Janin J (1991) "Protein–protein interaction: an analysis by computer simulation". In: Chadwick DJ and Widdows K (eds) Protein Conformation, pp. 237–252. Chichester, UK: Wiley
    book Garel JR (1992) "Folding of large proteins: multidomain and multisubunit proteins". In: Creighton TE (ed.) Protein Folding, pp. 405–454. New York: Freeman.
    Garel JR, Martel A, Muller K et al. (1984) Role of subunit interactions in the self-assembly of oligomeric proteins. Advances in Biophysics 18: 91–113.
    book Klotz IM, Darnell DW and Langerman NR (1975) "Quaternary structure of proteins". In: Neurath H and Hill RL (eds) The Proteins, 3rd edn, pp. 25–62. New York: Academic Press.
    Matthews BW and Bernhard SA (1973) Structure and symmetry of oligomeric enzymes. Annual Review of Biophysics and Bioengineering 2: 257–317.
    Riddihough G (1994) The evolution of oligomerization. Nature Structural Biology 1: 411–412.
    book Weber G (1992) Protein Interactions. London: Chapman and Hall.

Related Sub-Topics:

Protein Structure | Proteins: Structure, Function, Metabolism
Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

Article Title: Protein Quaternary Structure: Subunit–Subunit Interactions
 
How to Cite close
Jones, Susan, and Thornton, Janet M(Apr 2001) Protein Quaternary Structure: Subunit–Subunit Interactions. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0003120]