ABSTRACT
In the first few chapters we covered more or less all of the general principles that guide how proteins work. In Chapters 7 and 8 we started to investigate the kind of roles that proteins have in cells, and we have seen for example that many complicated systems, such as motors, have a common and fairly simple core, but that the workings of evolution tend to generate a patchwork or mosaic system, with components brought in from elsewhere wherever needed. This can generate systems of considerable complexity as well as redundancy. In Chapter 8 we saw how interactions between one domain and another build up specificity but can also facilitate cross-talk between one signaling system and another.
