ERGIC-53 KKAA signal mediates endoplasmic reticulum retrieval in yeast.
Studies on the ERGIC-53 KKAA signal have revealed a new mechanism for static retention of mammalian proteins in the endoplasmic reticulum (Andersson, H., Kappeler, F., Hauri, H. P. (1999): Protein targeting to endoplasmic reticulum by dilysine signals involves direct retention in addition to retrieval. J. Biol. Chem. 274,15080 - 15084). To test if this mechanism was conserved in yeast, the ERGIC-53 KKAA signal was transferred on two different yeast reporter proteins. Making use of a genetic assay, we demonstrate that this signal induces COPI-dependent ER retrieval. ER retention of KKAA-tagged proteins was impaired in yeast mutants affected in COPI subunits. Furthermore, biochemical analysis of post-ER carbohydrate modifications detected on reporter proteins indicated that KKAA-tagged proteins recycle continuously within early compartments of the secretory pathway. Therefore in yeast, the KKAA signal might only function as a classical dilysine ER retrieval signal.
Dogic
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Institut de Biologie et Chimie des Protéines, IBCP/UMR5086 CNRS Université Lyon I, France.
Dubois
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A
de Chassey
B
B
Lefkir
Y
Y
Letourneur
F
F
D050260:Carbohydrate Metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins / Q000378:metabolism* / Q000502:physiology; D021382:Protein Sorting Signals / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism
D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D021382:Protein Sorting Signals