Homodimers
Protein dimer
Macromolecular complex formed by two, usually non-covalently bound, macromolecules
In biochemistry, a protein dimer is a macromolecular complex or multimer formed by two protein monomers, or single proteins, which are usually non-covalently bound. Many macromolecules, such as proteins or nucleic acids, form dimers. The word dimer has roots meaning "two parts", di- + -mer. A protein dimer is a type of protein quaternary structure.
A protein homodimer is formed by two identical proteins while a protein heterodimer is formed by two different proteins.
Most protein dimers in biochemistry are not connected by covalent bonds. An example of a non-covalent heterodimer is the enzyme reverse transcriptase, which is composed of two different amino acid chains.[1] An exception is dimers that are linked by disulfide bridges such as the homodimeric protein NEMO.[2]
Some proteins contain specialized domains to ensure dimerization (dimerization domains) and specificity.[3]
The G protein-coupled cannabinoid receptors have the ability to form both homo- and heterodimers with several types of receptors such as mu-opioid, dopamine and adenosine A2 receptors.[4]