Many of the proteins of greatest human physiological and pharmaceutical relevance are of relatively low abundance. The Membrane Protein Expression Center (MPEC) focuses on high quality expression of eukaryotic proteins since prokaryotic membrane proteins are now expressed well, and since eukaryotic membrane proteins provide most therapeutically important targets. If a client seeks to express a prokaryotic membrane, protein procedures for rapid expression are available and can be harnessed.

Although membrane proteins can be expressed in recombinant form, there is a crucial need to apply more robust expression systems for all membrane proteins. For oligomeric membrane proteins, efficient co-expression of membrane protein subunits and assembly systems are applied.

Efficient methods to characterize the lipid and detergent contents, state of aggregation, physical homogeneity, and sequence microheterogeneity have been developed and are routinely applied. Protein characterization includes tests of uniformity of mass, purity, monomer/oligomer homogeneity, monodispersity. The functional state of the expressed and purified membrane proteins are assessed and provided to the client via web interface in real time here.

Structures determined for membrane proteins are one kind of gold standard for correctly folded, homogeneous membrane protein, prepared in quantity, and purified with high efficiency. To date most membrane protein structures have been solved for bacterial membrane proteins that can be expressed in bacteria, and for (only six) eukaryotic membrane proteins that are obtained from naturally rich sources (bovine retina, bovine heart, bovine eye lens etc.). This parallels the record of structure determination of soluble proteins 30 years ago. Thus it portrays a rapid expansion in ability to utilize modern methods in drug discovery or structure assisted drug discovery toward a traditionally intractable area, membrane proteins.

The expression and purification of eukaryotic membrane proteins will advance the forefront of eukaryotic membrane protein biology into the foreseeable future.The MPEC provides a centralized area for application of novel expression of eukaryotic membrane proteins, their purification and characterization. Organizations that seek to express membrane proteins may apply here. Proposals are ranked on entry to the MPEC and processed in parallel. The MPEC extensively uses robotic methods to achieve parallel expression of many membrane proteins with an ‘entry to exit’ time scale of about 3 months.