Synthesis of polyoma proteins in vitro

Polyoma virus DNA can be transcribed and translated in an extract of Escherichia coli. Proteolytic digests of the product contain peptides that correspond to peptides from the virion. One of the in vitro synthesized polypeptides corresponds in size to the major virion protein but most of the product is smaller in size than this protein. Although most of the tryptic peptides corresponding to the major virion protein can be detected in the in vitro synthesized polypeptides, all of them also gave rise to other, non-matching, peptides. Much of the in vitro product therefore appears to correspond to incomplete molecules of the major virion protein.