What is the Difference Between Homodimer and Heterodimer?

🆚 Go to Comparative Table 🆚

The main difference between a homodimer and a heterodimer lies in the identity of the protein monomers that form the dimer. A protein dimer is a macromolecular complex or multimer formed by two protein monomers, usually non-covalently bound. There are two types of protein dimers:

  1. Homodimer: A homodimer is formed by two identical proteins. These homodimers often exhibit some degree of symmetry and are common in catalysis and regulation.
  2. Heterodimer: A heterodimer is formed by two different proteins. Heterodimers are also common in catalysis and regulation, and they can be involved in various biochemical pathways.

Both homodimers and heterodimers play crucial roles in cellular processes, and their formation can be regulated by various factors. The choice between homodimerization and heterodimerization can depend on the specific context and function of the proteins involved.

Comparative Table: Homodimer vs Heterodimer

Here is a table comparing the differences between homodimers and heterodimers:

Feature Homodimer Heterodimer
Definition A protein dimer composed of two identical protein monomers. A protein dimer composed of two different protein monomers.
Structure The two monomers in a homodimer are the same, often implying some kind of symmetry. The two monomers in a heterodimer are different, resulting in a more complex structure.
Function Homodimers are common in catalysis and regulation, and can perform specialized functions in certain cases. Heterodimers are also common in catalysis and regulation, but their functions can be more diverse due to the different monomers involved.
Hydrophobic Residues Homodimers tend to have predominant hydrophobic residues, such as Ala, Val, Leu, Met, Ile, and Phe, at their interfaces. Heterodimers may have a different distribution of hydrophobic residues at their interfaces, depending on the specific proteins involved.
Examples Homodimers can be formed by proteins like EGFR ECD, which have nearly 50% homology and similar domains. Heterodimers can be formed by proteins like E2F-DP, which consists of the protein E2F and its dimerization partner, DP.

In summary, homodimers are composed of two identical protein monomers, while heterodimers are composed of two different protein monomers. These differences in structure lead to variations in function and hydrophobic residue distribution at the interfaces of homodimers and heterodimers.