Proteins shared by the transcription and translation machines

It is becoming increasingly clear that the complex machines involved in tra nscription and translation, the two major activities leading to gene expres sion, communicate directly with one another by sharing proteins. For some p roteins, such as ribosomal proteins S10 and L4, there is strong evidence of their participation in both processes, and much is known about their role in both activities. The exact roles and interactions of other proteins, suc h as Nus factors B and G, in both transcription and translation remain a my stery. Although there are not, at present, many examples of such shared pro teins, the importance of understanding their behavior and intimate involvem ent with two major cellular machines is beginning to be appreciated. Studie s related to the dual activities of these proteins and searches for more ex amples of proteins shared between the transcription and translation machine s should lead to a better understanding of the communication between these two activities and the purposes it serves.