The component of a membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region. [source:
GOC:dos, GOC:jl, GOC:mah]
Note that proteins extrinsic to membranes can be removed by treatments that do not disrupt the membrane, such as salt solutions.
Add usage comments for this term on the GONUTS wiki.