This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kim, Y. Articles by Pearce, D. A. Search for Related Content PubMed PubMed Citation Articles by Kim, Y. Articles by Pearce, D. A.

 Previous Article  |  Next Article 

Eukaryotic Cell, February 2005, p. 281-288, Vol. 4, No. 2
1535-9778/05/$08.00+0     doi:10.1128/EC.4.2.281-288.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Interaction among Btn1p, Btn2p, and Ist2p Reveals Potential Interplay among the Vacuole, Amino Acid Levels, and Ion Homeostasis in the Yeast Saccharomyces cerevisiae

Yoojin Kim,^1, Subrata Chattopadhyay,¹ Sarahjane Locke,¹ and David A. Pearce^1,2,3*

Center for Aging and Developmental Biology, Aab Institute of Biomedical Sciences,¹ Department of Biochemistry and Biophysics,² Department of Neurology, School of Medicine and Dentistry, University of Rochester, Rochester, New York³

Received 12 August 2004/ Accepted 11 November 2004

Btn2p, a novel cytosolic coiled-coil protein in Saccharomyces cerevisiae, was previously shown to interact with and to be necessary for the correct localization of Rhb1p, a regulator of arginine uptake, and Yif1p, a Golgi protein. We now report the biochemical and physical interactions of Btn2p with Ist2p, a plasma membrane protein that is thought to have a function in salt tolerance. A deletion in Btn2p (btn2 strains) results in a failure to correctly localize Ist2p, and strains lacking Btn2p and Ist2p (btn2 ist2 strains) are unable to grow in the presence of 0.5 or 1.0 M NaCl. Btn2p was originally identified as being up-regulated in a btn1 strain, which lacks the vacuolar-lysosomal membrane protein, Btn1p, and serves as a model for Batten disease. This up-regulation of Btn2p was shown to contribute to the maintenance of a stable vacuolar pH in the btn1 strain. Btn1p was subsequently shown to be required for the optimal transport of arginine into the vacuole. Interestingly, btn1 ist2 strains are also unable to grow in the presence of 0.5 or 1.0 M NaCl, and ist2 suppresses the vacuolar arginine transport defect in btn1 strains. Although further investigation is required, we speculate that altered vacuolar arginine transport in btn1 strains represents a mechanism for maintaining or balancing cellular ion homeostasis. Btn2p interacts with at least three proteins that are seemingly involved in different biological functions in different subcellular locations. Due to these multiple interactions, we conclude that Btn2p may play a regulatory role across the cell in response to alterations in the intracellular environment that may be caused by changes in amino acid levels or pH, a disruption in protein trafficking, or imbalances in ion homeostasis resulting from either genetic or environmental manipulation.

Present address: Vollum Institute, Oregon Health Sciences University, Portland, OR 97239.

This article has been cited by other articles:

• Efe, J. A., Botelho, R. J., Emr, S. D. (2007). Atg18 Regulates Organelle Morphology and Fab1 Kinase Activity Independent of Its Membrane Recruitment by Phosphatidylinositol 3,5-Bisphosphate. Mol. Biol. Cell 18: 4232-4244 [Abstract] [Full Text]  
• Eliason, S. L., Stein, C. S., Mao, Q., Tecedor, L., Ding, S.-L., Gaines, D. M., Davidson, B. L. (2007). A Knock-In Reporter Model of Batten Disease. J. Neurosci. 27: 9826-9834 [Abstract] [Full Text]  
• Vitiello, S. P., Wolfe, D. M., Pearce, D. A. (2007). Absence of Btn1p in the yeast model for juvenile Batten disease may cause arginine to become toxic to yeast cells. Hum Mol Genet 16: 1007-1016 [Abstract] [Full Text]  
• Kama, R., Robinson, M., Gerst, J. E. (2007). Btn2, a Hook1 Ortholog and Potential Batten Disease-Related Protein, Mediates Late Endosome-Golgi Protein Sorting in Yeast. Mol. Cell. Biol. 27: 605-621 [Abstract] [Full Text]  
• Padilla-Lopez, S., Pearce, D. A. (2006). Saccharomyces cerevisiae Lacking Btn1p Modulate Vacuolar ATPase Activity to Regulate pH Imbalance in the Vacuole. J. Biol. Chem. 281: 10273-10280 [Abstract] [Full Text]  
• Pears, M. R., Cooper, J. D., Mitchison, H. M., Mortishire-Smith, R. J., Pearce, D. A., Griffin, J. L. (2005). High Resolution 1H NMR-based Metabolomics Indicates a Neurotransmitter Cycling Deficit in Cerebral Tissue from a Mouse Model of Batten Disease. J. Biol. Chem. 280: 42508-42514 [Abstract] [Full Text]  
• Ramirez-Montealegre, D., Pearce, D. A. (2005). Defective lysosomal arginine transport in juvenile Batten disease. Hum Mol Genet 14: 3759-3773 [Abstract] [Full Text]