N-recognin/Ubc2 interactions in the N-end rule pathway.

摘要: Abstract The N-end rule relates the in vivo half-life of a protein to identity its N-terminal residue. In yeast Saccharomyces cerevisiae, substrates pathway are targeted for degradation by complex that includes 225-kDa N-recognin, encoded UBR1, and 20-kDa ubiquitin-conjugating enzyme UBC2. We report both physical stability functional activity N-recognin.Ubc2 require presence highly acidic 23-residue region at C terminus Ubc2. Ubc2-C88A, an inactive variant Ubc2 which active-site Cys-88 has been replaced Ala, is shown retain affinity N-recognin. Expression Ubc2-C88A inhibits pathway, apparently as result competition between binding two-hybrid (interaction cloning) technique was used identify approximately 170-residue C-terminal fragment 1,950-residue N-recognin Ubc2-interacting domain. also show level UBR1 mRNA decreases upon overexpression This effect UBC2 observed with cells whose expressed from unrelated promoter but not if contains frameshift mutation, or lacks region. appears regulate expression through changes metabolic mRNA.