Myelin proteolipid protein (PLP or lipophilin) is the major myelin protein from the central nervous system (CNS). It plays an important role in the formation or maintenance of the multilamellar structure of myelin. The myelin sheath is a multi-layered membrane, unique to the nervous system, that functions as an insulator to greatly increase the velocity of axonal impulse conduction.
In man point mutations in PLP are the cause of Pelizaeus-Merzbacher disease (PMD), a neurologic disorder of myelin metabolism. In animals dismyelinating diseases such as mouse 'jimpy' or dog 'shaking pup' are also caused by mutations in PLP.
PLP is a highly conserved hydrophobic protein of 276 to 280 amino acids which seems to contain four transmembrane segments, two disulfide bonds and which covalently binds lipids (at least six palmitate groups in mammals). PLP is highly related to GPM6A, a neuronal membrane glycoprotein.
^Weimbs T, Sto ffel W (1992). "Proteolipid protein (PLP) of CNS myelin: positions of free, disulfide-bonded, and fatty acid thioester-linked cysteine residues and implications for the membrane topology of PLP". Biochemistry31 (49): 12289–12296. doi:10.1021/bi00164a002. PMID1281423.