Crystallization in cubo: general applicability to membrane proteins.

Obtaining well ordered crystals of membrane proteins is the single most serious stumbling block in the pursuit of their high-resolution structures. The applicability of lipidic cubic phase-mediated crystallization is demonstrated on a diverse set of bacterial membrane proteins: two photosynthetic reaction centres, a light-harvesting complex and two retinal proteins, halorhodopsin and bacteriorhodopsin. Despite marked differences in molecular dimensions, subunit composition and membrane origin, one single lipid, monoolein, is sufficient to form a crystallization matrix for all the aforementioned systems. Therefore, the lipidic cubic phase approach is proposed as a general method for crystallizing membrane proteins.