Peripheral membrane protein

Definition
noun, plural: peripheral membrane proteins
A protein that temporarily adheres to the biological membrane, either to the lipid bilayer or to integral proteins by a combination of hydrophobic, electrostatic, and other non-covalent interactions.
Supplement
Peripheral membrane proteins are located on the peripheral regions of the lipid biliayer of biological membranes. Examples of peripheral membrane proteins are proteins involved in electron transport chains, such as cytochrome c, cupredoxins, high potential iron protein, adrenodoxin reductase, some flavoproteins, and others.
Other peripheral membrane proteins are the carriers of non-polar compounds that facilitate transport of phosphatidylinositol, tocopherol, gangliosides, glycolipids, sterol derivatives, retinol, or fatty acids.
Word origin: peripheral < periphery: LL peripherīa < Gk periphéreia circumference, lit., a bearing round + -al.
Synonym: extrinsic protein.

Compare: integral membrane protein.

See also: cell membrane, fluid mosaic model.