Plasma Membrane Proteolipid (PLLP)

Plasmolipin is an 18-kD proteolipid protein found in kidney and brain, where it is restricted to the apical surface of tubular epithelial cells and to myelinated tracts, respectively. Addition of plasmolipin to lipid bilayers induces the formation of ion channels, which are voltage-dependent and K(+)-selective.Northern blot analysis showed that plasmolipin is encoded by a 1.7-kb mRNA, confirmed that the distribution of plasmolipin is restricted to kidney and brain, and indicated that the expression of plasmolipin mRNA in cultured oligodendrocytes increases with cell maturation consistent with changes in the level of the protein. Southern blot analysis was consistent with encoding of plasmolipin by a single gene. The cDNA contained an open reading frame encoding a 157-amino acid protein of 17.4 kD.