Topology of the yeast Ras converting enzyme as inferred from cysteine accessibility studies.

The Ras converting enzyme (Rce1p) is an endoprotease that is involved in the post-translational processing of the Ras GTPases and other isoprenylated proteins. Its role in Ras biosynthesis marks Rce1p as an anticancer target. By assessing the chemical accessibility of cysteine residues substituted throughout the Saccharomyces cerevisiae Rce1p sequence, we have determined that yeast Rce1p has eight segments that are protected from chemical modification.