Alexander E. Aleshin

Alexander E. Aleshin is a researcher in structural biology credited with studies of the complement system. He was first author of the 2012 determination of the crystal structure of complement C6, with a Sanford-Burnham Medical Research Institute affiliation in the original byline.^[ref]

The biological problem was how soluble proteins assemble a membrane-damaging machine. Complement C6 is recruited during formation of the membrane attack complex. Its structure revealed a closed arrangement of protein domains. Comparing this arrangement with related components suggested how changes in domain orientation could help expose membrane-inserting regions and propagate assembly.^[ref]

A useful mechanical analogy is a folded tool whose working surface is inaccessible until a hinge opens. The analogy motivates two experimentally distinct questions: what configurations exist, and what causes transitions between them? Determining a crystal structure answers the first kind of question for the crystallized state; it does not directly film the assembly sequence.

The distinction is explicit in this work. The complement C6 coordinates and comparisons constrain a proposed model of directional membrane attack complex assembly. Testing the proposed succession of movements requires additional evidence about interacting components and assembly intermediates. Aleshin and colleagues thus connected a measured molecular shape to a testable explanation of a larger biological process.^[ref]