Protein trimer

Assembled human PCNA (PDB 1AXC), a sliding DNA clamp protein that is part of the DNA replication complex and serves as a processivity factor for DNA polymerase. The three individual polypeptide chains that make up the trimer are shown.

In biochemistry, a protein trimer is a macromolecular complex formed by three, usually non-covalently bound, macromolecules like proteins or nucleic acids. A protein trimer often occurs from the assembly of a protein's quaternary structure.[1] The non-covalent interactions between the hydrophobic and hydrophilic regions on the polypeptides units help to stabilize the quaternary structure. Since a protein trimer is composed of multiple polypeptide subunits, it is considered an oligomer.[2]

A homotrimer would be formed by three identical molecules. A heterotrimer would be formed by three different macromolecules. Type II Collagen is an example of homotrimeric protein, while Type I collagen is an AAB-type heterotrimeric protein.

Porins usually arrange themselves in membranes as trimers.

  1. ^ Godbey, W.T. (2014), "Proteins", An Introduction to Biotechnology, Elsevier, pp. 9–33, doi:10.1016/b978-1-907568-28-2.00002-2, ISBN 978-1-907568-28-2, retrieved 2024-05-03
  2. ^ Pelley, John W. (2012-01-01), Pelley, John W. (ed.), "3 - Protein Structure and Function", Elsevier's Integrated Review Biochemistry (Second Edition), Philadelphia: W.B. Saunders, pp. 19–28, doi:10.1016/b978-0-323-07446-9.00003-9, ISBN 978-0-323-07446-9, retrieved 2024-05-03