Multiprotein complex

A protein complex is a joint storage of multiple proteins. Only in this complex many proteins to perform their cellular function. Depending on context, a protein complex is also referred to as the quaternary structure, in analogy with the designations of the primary, secondary and tertiary structure of a protein three-dimensional viewing planes.

Construction

A protein complex may be either an assembly of different proteins, or an association of two or more polypeptide chains that are from the same polypeptide, the precursor protein, emerged (see: Insulin ). The individual proteins are often linked together by hydrogen bonds and salt bridges, but also by covalent bonds. The individual subunits of such a complex are called protomers. Some protomers can their function as stand-alone proteins have, but many achieve their functionality only in the complex. As an example of stored together from multiple proteins complexes, the immunoglobulins (antibodies) can be used, in which two identical heavy and two identical light proteins with a total of four disulfide bridges are connected to form a functional antibody.

Specific connection

Many protein domains impart very specific interaction between the proteins and thus provide the basis for the formation of protein complexes. Examples include the PDZ domains, ankyrin repeats, and many other domains.

Often also form specific scaffold proteins with such protein domains the basis of a protein complex in which they almost serve as a bridge between different proteins.

Methods of investigation

Many molecular biological methods may be used for the detection of protein complexes, especially in the field of proteomics, for example:

  • Fluorescence microscopy or confocal laser scanning microscopy for co-localization of proteins
  • FRET
  • Gel electrophoresis - denaturing and native gels
  • Immunoprecipitation combined with Western blotting or 2D gel electrophoresis
  • Yeast two-hybrid
  • Protein binding studies with atomic force microscopy
  • Structure determination by NMR and X-ray structure analysis
  • Protein Chip
Protein microarray
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