A family of proteins containing a conserved domain that mediates interaction with the yeast SNF1 protein kinase complex.
The SNF1 protein kinase is required for the regulatory response to glucose starvation in Saccharomyces cerevisiae. SNF1 is a protein serine/threonine kinase that has been widely conserved in both plants and mammals. Previously, we identified SIP1 and SIP2 as proteins that interact with SNF1 in vivo by the two-hybrid system. We have cloned the SIP2 gene and the encoded protein is homologous to SIP1 and to GAL83, which affects glucose repression of the GAL genes. We show that SIP2 and GAL83, like SIP1, co-immunoprecipitate with SNF1 and are phosphorylated in vitro. An 80 amino acid sequence, designated the ASC domain, is highly conserved at the C-termini of all three proteins. We show that this small domain can mediate protein-protein interaction with the SNF1 kinase complex. Thus, SIP1, SIP2 and GAL83 define a family of homologous proteins that are tightly associated with the SNF1 kinase, probably in alternative forms of the complex. Genetic evidence suggests that the three proteins have distinct, but related, functions in the SNF1 pathway, and deletion of GAL83 dramatically reduces SNF1 activity in immune complex assays. We propose that SIP1, SIP2 and GAL83 act as adaptors that promote the activity of SNF1 towards specific targets.
Yang
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Department of Genetics, College of Physicians and Surgeons of Columbia University, New York, NY 10032.
Jiang
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R
Carlson
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D055372:AMP-Activated Protein Kinases; D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D005656:Fungal Proteins / Q000378:metabolism*; D018628:Gene Dosage; D005947:Glucose / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism
D002352:Carrier Proteins; D005656:Fungal Proteins; C085569:GAL83 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C091267:SIP2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D011494:Protein Kinases; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; C075934:SIP1 protein, S cerevisiae; C078651:SNF4 protein, S cerevisiae; D055372:AMP-Activated Protein Kinases; D005947:Glucose