Membrane proteins are common proteins that are part of, or interact with, biological membranes. Membrane proteins fall into several broad categories depending on their location. Integral membrane proteins are a permanent part of a cell membrane and can either penetrate the membrane (transmembrane) or associate with one or the other side of a membrane (integral monotopic). Peripheral membrane proteins are transiently associated with the cell membrane.
Membrane proteins are common, and medically important—about a third of all human proteins are membrane proteins, and these are targets for more than half of all drugs.[1] Nonetheless, compared to other classes of proteins, determining membrane protein structures remains a challenge in large part due to the difficulty in establishing experimental conditions that can preserve the correct (native) conformation of the protein in isolation from its native environment.
- ^ Overington JP, Al-Lazikani B, Hopkins AL (December 2006). "How many drug targets are there?". Nature Reviews. Drug Discovery (Opinion). 5 (12): 993–6. doi:10.1038/nrd2199. PMID 17139284. S2CID 11979420.