The FKB2 gene of Saccharomyces cerevisiae, encoding the immunosuppressant-binding protein FKBP-13, is regulated in response to accumulation of unfolded proteins in the endoplasmic reticulum.
The FKB2 gene of Saccharomyces cerevisiae encodes a homolog of mammalian FKBP-13, an FK506/rapamycin-binding protein that localizes to the lumen of the endoplasmic reticulum (ER). We have found that FKB2 mRNA levels increase in response to the accumulation of unfolded precursor proteins in the ER. FKB2 mRNA levels are elevated in cells blocked in N-glycosylation--i.e., in wild-type cells treated with tunicamycin and in the sec53-6 mutant grown at the nonpermissive temperature. Mutations that block other steps in secretion have no effect on FKB2 mRNA levels, indicating that increases in FKB2 mRNA are not the consequence of a general block in secretion. The increase in FKB2 mRNA in response to unfolded proteins in the ER is mediated through a 21-bp unfolded-protein response (UPR) element located in the 5' noncoding region of FKB2. UPR elements present in other ER chaperone genes, such as yeast KAR2 (BiP), mammalian GRP78 (BiP), and GRP94, function in an analogous manner to that in FKB2. As with KAR2, FKB2 mRNA levels are also elevated by heat shock. The similarities in the regulation of FKB2 and other ER chaperone genes suggest that FKBP-13 may play a role in protein trafficking in the ER.
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Vertex Pharmaceuticals Incorporated, Cambridge, MA 02139-4211.
Berlin
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006358:Hot Temperature; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D017510:Protein Folding; D012333:RNA, Messenger / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D016559:Tacrolimus / Q000378:metabolism; D022021:Tacrolimus Binding Proteins; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C070133:FKBP-13; D001616:beta-Galactosidase; D022021:Tacrolimus Binding Proteins; D016559:Tacrolimus