Max Lönnfors

Åbo Akademi University
Supervisor: J. Peter Slotte
Funding: ISB
Date: 2012-01-01

How do lipids create order and lateral structure in bilayer membranes

The lateral distribution and formation of lipid domains in biological and model bilayer membranes is thought to be of importance for proper cellular functions. For example, some proteins have been shown to function properly only at the interface between an ordered and a disordered domain, others require a specific hydrophobic thickness only found in the ordered domains. It is also thought that lipid rafts can act as collectors for many proteins needed in a signaling pathway, bringing them together when needed for signal generation.

Sterols (mainly cholesterol) play an important role in maintaining membrane fluidity and regulating membrane permeability in biological membranes (Maxfield et al. 2010). Cholesterol will impose order to disordered lipids and also prevent ordered lipids from forming a gel phase (Ohvo-Rekilä et al. 2002). Cholesterol will thicken the membrane (because of acyl chain ordering), and this is believed to be important for the function of some proteins (e.g., Na+/K+-ATPase). Since cholesterol, together with sphingomyelin , are important constituents of lipid rafts, it is of the importance to better understand how the lateral distribution of these lipids is regulated, and how the properties of the involved lipids and sterols affect this distribution.

In my projects I study sterol interactions with sphingolipids, and how modifications to sterol and sphingolipid structure affects interactions and the formation of lateral ordered domains in fluid bilayer membranes. I will also study plasma membrane derived giant vesicles and try to understand the role of cholesterol and sphingolipids in the formation of a liquid-ordered phase.