Isolation and characterization of SUG2: A novel ATPase family component of the yeast 26 S proteasome

Steven Jon Russell, Ubaradka G. Sathyanarayana, Stephen Albert Johnston

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


Using a genetic strategy designed to find proteins involved in the function of the Saccharomyces cerevisiae transcriptional activator GAL4, we isolated mutants in two genes which rescue a class of gal4 activation domain mutants. One of these genes, SUG1, encodes a member of a large family of putative ATPases, the Conserved ATPase containing Domain (CAD) proteins (also known as AAA proteins) that are involved in a wide variety of cellular functions. Subsequently, SUG1 was identified as a subunit of the 26 S proteasome. We have now cloned the gene defined by the second complementation group. SUG2 encodes an essential 49-kDa protein that is also a member of the CAD family and is 43% identical to SUG1. The mutation in sug2-1, like that in sug1-1, is found in the CAD near the highly conserved ATPase motif. We present biochemical and genetic evidence that SUG2 is associated in vivo with SUG1 and is a novel CAD protein subunit of the 26 S proteasome. With its highly conserved mammalian homologs, human p42 and ground squirrel CADp44, SUG2 defines a new class of proteasomal CAD proteins.

Original languageEnglish (US)
Pages (from-to)32810-32817
Number of pages8
JournalJournal of Biological Chemistry
Issue number51
StatePublished - 1996
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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