ABSTRACT
Since the early 1990s, an increasing number of crystal structures of integral membrane proteins have appeared in the literature, many of which have been hailed as stunning breakthroughs (1, 2). Nonetheless, the crystallographic analysis of membrane proteins still remains difficult, for one simple reason: Straightforward and routine methodologies for obtaining X-rayquality crystals are still rudimentary. This sobering statement contrasts markedly with the current state of structural analysis for soluble proteins, where “high-throughput” crystallography is in vogue in this postgenomic era. Nonetheless, integral membrane proteins represent at least 25% of the proteins encoded in the genomes of most organisms (3), and they include many potential sites for drug development. This has spurred new efforts to crystallize integral membrane proteins.
