Crystallization of Cytokine-Receptor Complexes

Crystallography is the most powerful method for determining the three-dimensional structure of complicated biological molecules. As the technology has improved, larger and more complicated structures involving previously unobtainable proteins have become available. Synchrotron radiation sources, fast and highly sensitive detectors, and cryogenic techniques have dramatically decreased the number and the size of crystals required for the analysis. Molecular biology techniques have allowed investigators to prepare milligram quantities of cytokines and their receptors that were previously extremely difficult to study because of their scarcity. Furthermore, mutations to remove naturally flexible or intramembranous domains make the preparation of specific cytokine-receptor complexes much more reasonable. However, the critical step is still the growth of crystals of macromolecules having sufficient size and quality to permit X-ray analysis.