The short-lived MAT alpha 2 transcriptional regulator is ubiquitinated in vivo.
The substrates of ubiquitin-dependent proteolytic pathways include both damaged or otherwise abnormal proteins and undamaged proteins that are naturally short-lived. Few specific examples of the latter class have been identified, however. Previous work has shown that the cell type-specific MAT alpha 2 repressor of the yeast Saccharomyces cerevisiae is an extremely short-lived protein. We now demonstrate that alpha 2 is conjugated to ubiquitin in vivo. More than one lysine residue of alpha 2 can be joined to ubiquitin, and some of the ubiquitin moieties form a Lys48-linked multiubiquitin chain. Overexpression of degradation-impaired ubiquitin variants was used to show that at least a significant fraction of alpha 2 degradation is dependent on its ubiquitination.
Hochstrasser
M
M
Department of Biochemistry and Molecular Biology, University of Chicago, IL 60637.
Ellison
M J
MJ
Chau
V
V
Varshavsky
A
A
D000595:Amino Acid Sequence; D005656:Fungal Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D005800:Genes, Fungal; D016259:Genes, myc; D018398:Homeodomain Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D011499:Protein Processing, Post-Translational; D012097:Repressor Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic; D014452:Ubiquitins / Q000378:metabolism*
D005656:Fungal Proteins; D018398:Homeodomain Proteins; C062928:MATA2 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins