Molecular cloning and expression of a 26 S protease subunit enriched in dileucine repeats.
The 26 S protease is a multisubunit enzyme required for ubiquitin-dependent proteolysis. Recently, we identified a 50-kDa subunit (S5) of this enzyme that binds ubiquitin polymers (Deveraux, Q., Ustrell, V., Pickart, C., and Rechsteiner, M. (1994) J. Biol. Chem. 269, 7059-7061). We have now isolated, sequenced, and expressed a cDNA encoding a novel 50-kDa subunit of the 26 S protease. The recombinant protein does not bind ubiquitin polymers. Two-dimensional electrophoresis reveals that two subunits of the 26 S protease have apparent molecular masses of 50 kDa. Antibodies specific for the recombinant protein recognize the more basic of the two subunits (S5b), whereas the more acidic subunit (S5a) binds ubiquitin chains. Thus, the 26 S protease contains at least two distinct subunits with apparent molecular masses of 50 kDa.
Deveraux
Q
Q
Department of Biochemistry, University of Utah School of Medicine, Salt Lake City 84132, USA.
Jensen
C
C
Rechsteiner
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D007930:Leucine / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014452:Ubiquitins / Q000378:metabolism
D018076:DNA, Complementary; D010446:Peptide Fragments; D011994:Recombinant Proteins; D014452:Ubiquitins; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D007930:Leucine