Insights into the structure of the CCR4-NOT complex by electron microscopy.

The CCR4-NOT complex is a deadenylation complex, which plays a major role for mRNA stability. The complex is conserved from yeast to human and consists of nine proteins NOT1-NOT5, CCR4, CAF1, CAF40 and CAF130. We have successfully isolated the complex using a Protein A tag on NOT1, followed by cross-linking on a glycerol gradient. All components of the complex were identified by mass spectrometry. Electron microscopy of negatively stained particles followed by image reconstruction revealed an L-shaped complex with two arms of similar length. The arms form an accessible cavity, which we think could provide an extensive interface for RNA-deadenylation.