ABSTRACT
Membrane proteins are a diverse group of proteins that are integral to the structure and function of biological membranes. They play a crucial role in a variety of cellular processes, including signalling, transport, and energy production. Dimerisation, the process of two identical (homodimer) or different (heterodimer) proteins coming together to form a functional unit, is a common phenomenon among membrane proteins. The platelet receptor GPVI is a good example of a membrane receptor which is functional as a dimer. Dimerisation can have a profound impact on the structure and function of membrane proteins, as well as on the properties of the membranes themselves. As we have seen in previous chapters, the oligomerisation or clustering of membrane proteins is a key biophysical factor in determining and regulating their function. Single-molecule microscopy methods are well suited when clusters contain several (or many) proteins. SMLM is less well suited to studying small oligomers such as dimers and trimers. This is because, especially when the density of membrane proteins is high, two proteins in close proximity can occur frequently by chance. This combined with the relatively poor SMLM localisation precision (10-30 nm) compared to a dimer size (1-10 nm) means that detecting dimerisation above noise is difficult. In these cases, Forster resonance energy transfer is probably the method of choice for detecting and analysing membrane protein dimerisation.
