NEW PERSPECTIVES ON THE STRUCTURE AND FUNCTION OF UBIQUITIN

Ubiquitin has been suggested to play a key role in a wide variety of essential cellular functions ranging from differential regulation of gene expression to protein degradation. Recent studies on natural and synthetic ubiquitin gene fusions have led to important discoveries concerning novel functions for the ubiquitin system in cells, mechanisms of proteolytic processing, and the development of a ubiquitin fusion technology for augmenting the expression of heterologous gene products in bacteria and yeast. Furthermore, studies involving site-directed mutagenesis and two-dimensional NMR have proven ubiquitin to be an excellent model for protein engineering and have led to important discoveries concerning its mechanism of action in ATP-dependent proteolysis. Finally, the recent identification and characterization of ubiquitin carboxyl extension proteins as ribosomal proteins has opened up an even newer area of ubiquitin-related research and has helped to explain the mechanisms involved in increasing the expression of heterologous gene products made as ubiquitin fusions. © 1990 Nature Publishing Group.