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Definition

noun, plural: intrinsic proteins

Any of the group of integral membrane proteins that facilitate specific transport of water molecules (e.g. by aquaporins), and of neutral solutes (e.g. glycerol by glycerol facilitators).

Supplement

Examples of intrinsic proteins are:

• Mammalian major intrinsic protein (MIP), which is the major component of lens fibre gap junctions.
• Mammalian aquaporins, which form water-specific channels.
• Bacterial glycerol facilitator protein, which facilitates the movement of glycerol across the cell membrane.

Word origin: ML intrinsecus inward (adjective), L (adverb), equiv. to intrin- (int(e)r-.

Synonym: integral membrane protein (IMP).
Compare: extrinsic protein.
See also: cell membrane, fluid mosaic model.