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  Significance of GTP hydrolysis in Ypt1p-regulated endoplasmic reticulum to Golgi transport revealed by the analysis of two novel Ypt1-GAPs

De Antoni, A., Schmitzova, J., Trepte, H. H., Gallwitz, D., & Albert, S. (2002). Significance of GTP hydrolysis in Ypt1p-regulated endoplasmic reticulum to Golgi transport revealed by the analysis of two novel Ypt1-GAPs. Journal of Biological Chemistry, 277(43), 41023-41031. Retrieved from http://www.jbc.org/content/277/43/41023.full.pdf+html.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0012-F2B9-7 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0028-E230-C
Genre: Journal Article

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 Creators:
De Antoni, A.1, Author              
Schmitzova, J.2, Author              
Trepte, H. H.1, Author              
Gallwitz, D.1, Author              
Albert, S.1, Author              
Affiliations:
1Department of Molecular Genetics, MPI for biophysical chemistry, Max Planck Society, ou_578622              
2Department of Cellular Biochemistry, MPI for biophysical chemistry, Max Planck Society, ou_578576              

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 Abstract: We here report on the identification and detailed biochemical characterization of two novel GTPase-activating proteins, Gyp5p and Gyp8p, whose efficient substrate is Ypt1p, a Ypt/Rab-GTPase essential for endoplasmic reticulum-to-Golgi trafficking in yeast. Gyp5p, accelerated the intrinsic GTPase activity of Ypt1p 4.2 X 10(4)-fold and, surprisingly, the 40-fold reduced GTP hydrolysis rate of Ypt1 (Q67L)p 1.5 x 10(4)-fold. At steady state, the two newly discovered GTPase-activating proteins (GAPs) as well as the previously described Gyp1p, which also uses Ypt1p as the preferred substrate, display different sulicellular localization. To add to an understanding of the significance of Ypt1p-bound GTP hydrolysis in vivo, yeast strains expressing the GTPase-deficient Ypt1(Q67L)p and having different Ypt1-GAP genes deleted were created. Depending on the genetic background, different mutants exhibited growth defects at low temperature and, already at permissive temperature, various morphological alterations resembling autophagy. Transport of proteins was not significantly impaired. Growth defects of Ypt1(Q67L)expressing cells could be suppressed on high expression of all three Ypt1-GAPs. We propose that permanently active Ypt1p leads to increased vesicle fusion, which might induce previously unnoticed autophagic degradation of exaggerated membrane-enclosed structures. The data indicate that hydrolysis of Ypt1p-bound GTP is a prerequisite for a balanced vesicle flow between endoplasmic reticulum and Golgi compartments.

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Language(s): eng - English
 Dates: 2002-10-25
 Publication Status: Published in print
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 Rev. Method: Peer
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Title: Journal of Biological Chemistry
Source Genre: Journal
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Pages: - Volume / Issue: 277 (43) Sequence Number: - Start / End Page: 41023 - 41031 Identifier: -