title: Rad23 escapes degradation because it lacks a proteasome initiation region.
abstract: Rad23 is an adaptor protein that binds to both ubiquitinated substrates and to the proteasome. Despite its association with the proteasome, Rad23 escapes degradation. Here we show that Rad23 remains stable because it lacks an effective initiation region at which the proteasome can engage the protein and unfold it. Rad23 contains several internal, unstructured loops, but these are too short to act as initiation regions. Experiments with model proteins show that internal loops must be surprisingly long to engage the proteasome and support degradation. These length requirements are not specific to Rad23 and reflect a general property of the proteasome.
authors.affiliation: Department of Molecular Biosciences, Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Fishbain
authors.forename: Sumit
authors.initials: S
authors.lastname: Prakash
authors.forename: Annie
authors.initials: A
authors.lastname: Herrig
authors.forename: Suzanne
authors.initials: S
authors.lastname: Elsasser
authors.forename: Andreas
authors.initials: A
authors.lastname: Matouschek
mesh_terms: D000595:Amino Acid Sequence; D003575:Cytochromes c1 / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016014:Linear Models; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D058767:Protein Unfolding; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; C490846:RAD23 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D003575:Cytochromes c1; D046988:Proteasome Endopeptidase Complex