Brij detergents reveal new aspects of membrane microdomain in erythrocytes

Author(s)

Casadei, Bruna Renata ^[1] ; Carvalho, Patricia De Oliveira ^[2] ; Riske, Karin A. ^[3] ; Barbosa, Raquel De Melo ^[1] ; De Paula, Eneida ^[1] ; Domingues, Cleyton Crepaldi ^[1]

Affiliation

^[1] Univ Estadual Campinas Unicamp, Inst Biol, Dept Bioquim & Biol Tecidual, Campinas, SP - Brazil

^[2] Univ Sao Francisco, Lab Multidisciplinar Pesquisa, BR-12900000 Braganca Paulista, SP - Brazil

^[3] Univ Fed Sao Paulo Unifesp, Dept Biofis, Sao Paulo - Brazil

• Document type: Journal article
• Source: MOLECULAR MEMBRANE BIOLOGY; v. 31, n. 6, p. 195-205, SEP 2014.
• Web of Science Citations: 7

Abstract

Membrane microdomains enriched in cholesterol, sphingolipids (rafts), and specific proteins are involved in important physiological functions. However their structure, size and stability are still controversial. Given that detergent-esistant membranes (DRMs) are in the liquid-ordered state and are rich in raft-like components, they might correspond to rafts at least to some extent. Here we monitor the lateral order of biological membranes by characterizing DRMs from erythrocytes obtained with Brij-98, Brij-58, and TX-100 at 4 degrees C and 37 degrees C. All DRMs were enriched in cholesterol and contained the raft markers flotillin-2 and stomatin. However, sphingomyelin (SM) was only found to be enriched in TX-100-DRMs -a detergent that preferentially solubilizes the membrane inner leaflet -while Band 3 was present solely in Brij-DRMs. Electron paramagnetic resonance spectra showed that the acyl chain packing of Brij-DRMs was lower than TX-100-DRMs, providing evidence of their diverse lipid composition. Fatty acid analysis revealed that the SM fraction of the DRMs was enriched in lignoceric acid, which should specifically contribute to the resistance of SM to detergents. These results indicate that lipids from the outer leaflet, particularly SM, are essential for the formation of the liquid-ordered phase of DRMs. At last, the differential solubilization process induced by Brij-98 and TX-100 was monitored using giant unilamellar vesicles. This study suggests that Brij and TX-100-DRMs reflect different degrees of lateral order of the membrane microdomains. Additionally, Brij DRMs are composed by both inner and outer leaflet components, making them more physiologically relevant than TX-100-DRMs to the studies of membrane rafts. (AU)

• FAPESP's process: 09/00904-1 - Effect of different surfactants and protocol changes (temperature and ionic strength changes, cholesterol depletion and local anesthetics) in detergent resistant membranes of erythrocytes
• Grantee: Eneida de Paula
• Support type: Regular Research Grants
• FAPESP's process: 10/18516-5 - Caracterization of erythrocyte membrane domains obtained with or without detergent
• Grantee: Cleyton Crepaldi Domingues
• Support type: Scholarships in Brazil - Post-Doctorate