Transbilayer peptide sorting between raft and nonraft bilayers: comparisons of detergent extraction and confocal microscopy.

Published

Journal Article

Membrane microdomains ("rafts") that sequester specific proteins and lipids are often characterized by their resistance to detergent extraction. Because rafts are enriched in sphingomyelin and cholesterol, raft bilayers are thicker and have larger area compressibility moduli than nonraft bilayers. It has been postulated that rafts concentrate proteins with long transmembrane domains (TMDs) because of "hydrophobic matching" between the TMDs and the thick raft bilayers. However, previous detergent extraction experiments with bilayers containing raft and nonraft domains have shown that the peptides P-23 and P-29, designed to have single TMDs matching the hydrocarbon thicknesses of detergent soluble membranes and detergent resistant membranes, respectively, are both localized to detergent soluble membranes. Those results imply that both peptides are preferentially located in nonraft domains. However, because the detergent solubilizes part of the bilayer, it has been unclear whether or not detergent extraction experiments provide an accurate indication of the location of peptides in intact bilayers. Here we use confocal microscopy to examine the distribution of these same peptides in intact bilayers containing both raft and nonraft domains. At 20 degrees C and 37 degrees C, P-23 and P-29 were both primarily localized in fluorescently labeled nonraft domains. These confocal results validate the previous detergent extraction experiments and demonstrate the importance of bilayer cohesive properties, compared to hydrophobic mismatch, in the sorting of these peptides that contain a single TMD.

Full Text

Duke Authors

Cited Authors

  • Vidal, A; McIntosh, TJ

Published Date

  • August 2005

Published In

Volume / Issue

  • 89 / 2

Start / End Page

  • 1102 - 1108

PubMed ID

  • 15908585

Pubmed Central ID

  • 15908585

International Standard Serial Number (ISSN)

  • 0006-3495

Digital Object Identifier (DOI)

  • 10.1529/biophysj.105.062380

Language

  • eng

Conference Location

  • United States