# Workshop on Lateral Membrane Heterogeneity

16-17 October 2019
US/Eastern timezone

### Shull Wollan Center (ORNL Building 8630) - Room A202

Functional heterogeneities, or so-called “rafts” in biological membranes, have proven difficult to study systematically owing in part, to their chemical complexity that is manifested, in part, by the hundreds of distinct lipid species that are contained within them. Different model systems [1,2] provide a bottom-up approach to the study of membranes and have proven to be valuable tools for understanding membrane structure and function. For example, x-ray and neutron scattering from spherical vesicles has provided a better understanding of lateral bilayer structure [2], and its dependence on headgroup and acyl chain properties of individual lipids. However, key aspects of lateral organization, including the coexistence of ordered and disordered fluid phases, their functionalities and physiological significance in the presence of transmembrane proteins, peptides and hormones, to name a few, remain to be addressed [3]. Another fundamental question is how the two lipid bilayer leaflets interact and influence each other’s structure and dynamics. A related open question is the extent to which membrane heterogeneities function under different physiological conditions [4,5]. A powerful means by which the lateral organization of rafts can be studied is through the analysis of their functionalized conditions via a combination of new theoretical/computational frameworks and state-of-the-art experimental techniques. Importantly, these functional rafts must be consistent with the physics and chemistry of the heterogeneous lipid composition, including any microscale phase separation processes.

The purpose of this workshop will be to bring together experts in both the biological function of membrane heterogeneities and in the physical and chemical properties of these materials in an effort to build new collaborations and encourage new interdisciplinary interactions.

### Organizing Committee

• John Katsaras (Oak Ridge National Laboratory/University of Tennessee)

• Maxim Lavrentovich (University of Tennessee)

• Dima Bolmatov (University of Tennessee)
References
1. M. Lavrentovich et al., First-order patterning transitions on a sphere as a route to cell morphology, Proc. Natl. Acad. Sci. U.S.A. 113(19), 5189-5194 (2016).
2. V. N. P. Anghel, D. Bolmatov, and J. Katsaras, Models for randomly distributed nanoscopic domains on spherical vesicles, Phys. Rev. E 97, 062405 (2018).
3. K. Jacobson, O. G. Mouritsen, and R. G. W. Anderson, Lipid rafts: at a crossroad between cell biology and physics, Nature Cell Biol. 9, 7-14 (2007)
4. J. C. Stachowiak et al., Phase-Separated Liposomes Enhance the Efficiency of Macromolecular Delivery to the Cellular Cytoplasm, Cellular and Molecular Bioengineering 10, 387-403 (2017)
5. L. J. Pike, Lipid rafts: heterogeneity on the high seas, Biochem. J. 378, 281-292 (2004)
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US/Eastern