  Influence of the 524-VAAEIL-529 sequence of annexins A6 in their interfacial behavior and interaction with lipid monolayers.; Nasir, Mehmet Nail  ; et alin Journal of Colloid & Interface Science (2013), In Press Annexin A6 (AnxA6), a calcium- and membrane-binding protein, is expressed in mammalian cells in two isoforms: AnxA6-1 and AnxA6-2, the latter lacking the 524- VAAEIL-529 sequence at the start of repeat 7 ... [more ▼] Annexin A6 (AnxA6), a calcium- and membrane-binding protein, is expressed in mammalian cells in two isoforms: AnxA6-1 and AnxA6-2, the latter lacking the 524- VAAEIL-529 sequence at the start of repeat 7. The different intracellular localization of these two isoforms suggests distinct function in membrane dynamics. The aim of this work was to analyze the behavior of AnxA6 isoforms at the air/water interface alone and in the presence of membrane mimicking lipid monolayers. Using Langmuir technique showed that AnxA6-2 was less adsorbed to the neat air-water interface than AnxA6-1 at acidic pH and minor differences in their PM-IRRAS spectra were observed. Both isoforms exhibited similar behavior towards cholesterol monolayer. However, the interactions of AnxA6-2 with cholesterol ester monolayer were most favorable compared to AnxA6-1. Our experimental data are discussed in relation with the different intracellular localization of the two isoforms and with our constructed model of AnxA6-2 with the known crystal structure of AnxA6-1 showing the persistence of the 516-529 α- helix in AnxA6-2 despite the absence of the 524-VAAEIL-529 sequence. [less ▲] Detailed reference viewed: 5 (3 ULg)Annexins as organizers of cholesterol- and sphingomyelin-enriched membrane microdomains in Niemann-Pick type C disease.; Nasir, Mehmet Nail ; et alin Cellular and Molecular Life Sciences : CMLS (2011), 69(11), 1773-1785 Growing evidence suggests that membrane microdomains enriched in cholesterol and sphingomyelin are sites for numerous cellular processes, including signaling, vesicular transport, interaction with ... [more ▼] Growing evidence suggests that membrane microdomains enriched in cholesterol and sphingomyelin are sites for numerous cellular processes, including signaling, vesicular transport, interaction with pathogens, and viral infection, etc. Recently some members of the annexin family of conserved calcium and membrane-binding proteins have been recognized as cholesterol-interacting molecules and suggested to play a role in the formation, stabilization, and dynamics of membrane microdomains to affect membrane lateral organization and to attract other proteins and signaling molecules onto their territory. Furthermore, annexins were implicated in the interactions between cytosolic and membrane molecules, in the turnover and storage of cholesterol and in various signaling pathways. In this review, we focus on the mechanisms of interaction of annexins with lipid microdomains and the role of annexins in membrane microdomains dynamics including possible participation of the domain-associated forms of annexins in the etiology of human lysosomal storage disease called Niemann-Pick type C disease, related to the abnormal storage of cholesterol in the lysosome-like intracellular compartment. The involvement of annexins and cholesterol/sphingomyelin-enriched membrane microdomains in other pathologies including cardiac dysfunctions, neurodegenerative diseases, obesity, diabetes mellitus, and cancer is likely, but is not supported by substantial experimental observations, and therefore awaits further clarification. [less ▲] Detailed reference viewed: 14 (2 ULg) |
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