We connect transistors and proteins in two ways. The first is by showing that they have much in common as fundamental devices of electronics and life. The second is by describing how an evolvable wiring of electronic devices can parallel the wiring of proteins into genetic regulatory networks. We then transform this connection into a methodology for the study of the evolutionary properties of circuits. The approach is based on the use of analog electronic circuit simulators. We present an example of implementation with the first results obtained