Heterologous

In medicine a heterologous transplant means 'between species' or 'from one species to another'.

In protein quaternary structure a heterologous interface is a subunit-subunit interface which occurs between different sequence regions of the protein subunit. All hetero-oligomeric interfaces are heterologous by definition, occurring between different subunits. However, homo-oligomeric interfaces are only rarely heterologous. In contrast, homo-oligomers tend to have isologous interfaces.

Assuming a symmetrical subunit assembly, only homo-oligomers with five or more subunits can have heterologous interfaces.