The 2.2 A crystal structure of the Ras-binding domain of the serine/threonine kinase c-Raf1 in complex with Rap1A and a GTP analogue

Protein-protein interactions. Putting the pieces together

What do the recently determined crystal structures of 14-3-3 proteins and of a complex between part of the protein kinase Raf and the Ras-related protein Rap tell us about how 14-3-3 and Ras regulate the function of Raf?

Ras-effector interactions, the problem of specificity

Ras plays the role of a molecular switch in many cellular signalling pathways. The Raf-kinase has been identified as the direct target molecule of Ras in mammalian cells. However, in recent reports other proteins have been characterised as putative Ras effectors which have neither a functional nor a structural relationship to each other. In addition it has been shown that also other members of the Ras family like Rap and R-Ras can interact with some of these proteins. To address the problem of specificity and of biological relevance of the interactions, they have to be carefully quantified and the cellular localisation of the proteins involved taken into account.

How Ras works: structure of a Rap-Raf complex

The three-dimensional structure of the complex between Rap and the 'Ras-binding domain' of Raf could be the prototype for a G protein-effector interaction.