G protein-coupled receptor dimers: look like their parents, but act like teenagers!

G protein-coupled receptors (GPCRs) represent the largest group of cell surface receptors and an important pharmacological target. Though originally thought to act in a one receptor-one effector fashion, it is now known that these receptors are capable of oligomerization and can function as dimers or higher order oligomers in native tissue. They do not only assemble with identical receptors as homodimers, but also associate with different GPCRs to form heterodimers. We discuss here how heterodimeric GPCRs can assemble, traffic and signal in a manner distinct from their individual receptor components or from homodimers. These receptor pairs are also demonstrated to be regulated by different chaperones, Rabs and scaffolding proteins, further emphasizing their potential as unique targets. We believe in the importance of investigating each GPCR heterodimer as an individual signaling complex, as they appear to act differently from each monomer constituting them. Just as teenagers may resemble their parents and share their genetic makeup, they can still act in a manner that is entirely unique!