Plasma Membrane Packing Asymmetry Drives Transmembrane Protein Localization

Protein asymmetry in chick synaptosomal plasma membrane.

The topographical arrangement of chick synaptosomal plasma membrane polypeptides was examined by lactoperoxidase-catalyzed iodination and trypsin digestion of proteins exposed at the exterior surface. The ““I-labeling profile on sucrose gradients of lysed, subfractionated synaptosomes generally coincided with the activity of the membrane marker (Na+-K+)-activated ATPase, which suggested that la...

Plasma membrane phospholipid asymmetry.

SecA drives transmembrane insertion of RodZ, an unusual single-span membrane protein.

The transmembrane (TM) helices of most type II single-span membrane proteins (S-SMPs) of Escherichia coli occur near the N-terminus, where the cell's targeting mechanisms can readily identify it as it emerges from the ribosome. However, the TM helices of a few S-SMPs, such as RodZ, occur a hundred or more residues downstream from the N-terminus, which raises fundamental questions about targetin...

Regulation of transbilayer plasma membrane phospholipid asymmetry.

Lipids in biological membranes are asymmetrically distributed across the bilayer; the amine-containing phospholipids are enriched on the cytoplasmic surface of the plasma membrane, while the choline-containing and sphingolipids are enriched on the outer surface. The maintenance of transbilayer lipid asymmetry is essential for normal membrane function, and disruption of this asymmetry is associa...

Lipid packing drives the segregation of transmembrane helices into disordered lipid domains in model membranes.

Cell membranes are comprised of multicomponent lipid and protein mixtures that exhibit a complex partitioning behavior. Regions of structural and compositional heterogeneity play a major role in the sorting and self-assembly of proteins, and their clustering into higher-order oligomers. Here, we use computer simulations and optical microscopy to study the sorting of transmembrane helices into t...