Figure 1.

The mPheS selection assay yields N-end degradation signals of varying strengths. (A) The SUMO-mPheS protein used for the selection contains five randomized residues that become the N-terminal amino acids of mPheS following cleavage by the SUMO protease (arrow). (B) List of N-terminal tags that passed the selection and directed degradation in vivo. (C) Turnover of selected mPheS variants in wild-type cells was assayed at different times after stopping translation. The sample lacking SUMO protease expressed SUMO-YLFVQ-mPheS. N.E. clone is a nonexpressing isolate.