MICROSCOPY Vol.44▶No.1 2009
â– Lectures

Structural analysis of MAPEG family proteins by electron crystallography

Nobuhiko Gyobu and Kaoru Mitsuoka

Abstract: We determined the atomic structures of two MAPEG family proteins, microsomal glutathione transferase 1 and mirosomal prostaglandin E synthase 1, by electron crystallography. Here we present the structural features of the proteins and discuss their relationship with the functions. The two membrane proteins are enzymes; the former can accept various substrates for the catalysis, while the latter has the specific substrate, prostaglandin H2. Based on the structural analysis of both proteins, we propose the mechanism that could explain the functional divergence. In addition, using the structural study of MAPEG family proteins as an example, we introduce the current status of electron crystallography, from two-dimensional crystallization to data analysis. This technique needs more research and development compared with X-ray crystallography, but it has unique advantages and is one of powerful approaches for the structural analysis of membrane proteins, which is now easy to try.

Key words: MAPEG super family, two-dimensional crystal, membrane protein, three-dimensional structure, cryo-electron microscopy