July 18, 2011

BAR domains are not just regions in a cell where proteins gather for a pint after a long day of cell division, migration, and sorting. No, BAR domains are regions on certain proteins that are able to bend membranes. This comes in handy for vesicle formation during endocytosis, and according to a recent paper, for plasma membrane organization.

Eisosomes are regions on the plasma membrane in budding yeast that are important for plasma membrane organization. They are positioned at the plasma membrane, where they sort membrane proteins and signaling molecules into small membrane invaginations. There is a long list of proteins found at eisosomes, many of which are uncharacterized. A recent paper looks at the functions of two core eisosome proteins – Pil1 and Lsp1. Olivera-Couto and colleagues found that these two proteins contain BAR domains, which are able to sense and change the curvature of membranes. Images above are electron micrographs of liposomes, which are artificially made vesicles. Untreated liposomes (top) are round, while vesicles treated with purified Pil1 or Lsp1 (middle and bottom) had tubules (arrows) deformed from the vesicles, showing that these proteins are capable of bending membranes.

Olivera-Couto, A., Grana, M., Harispe, L., & Aguilar, P. (2011). The eisosome core is composed of BAR domain proteins Molecular Biology of the Cell, 22 (13), 2360-2372 DOI: 10.1091/mbc.E10-12-1021