Prokaryotic polyprotein precursors.

Polyproteins have been found only recently in prokaryotes. The four known examples of single bacterial genes encoding precursors that are posttranslationally processed into two mature proteins are addressed here with respect to (i) their genomic arrangement, (ii) the sites of proteolytic processing, (iii) the relevant proteases, (iv) their maturation pathway, and (v) the function of the mature proteins. How these polyproteins may have evolved is also discussed.