Biosketch Top
In 1989, Dr. Krämer completed his Ph.D. at the University of Cologne, Germany, where he worked on DNA looping in the lac operon. As a postdoctoral fellow in the lab of Dr. Larry Zipursky at UCLA, he studied cell-cell interactions during neuronal differentiation in the compound eye of Drosophila. In 1993, he joined UT Southwestern Medical Center at Dallas as an Assistant Professor in Cell Biology and Neuroscience.
Research Top
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Research in Dr. Krämer’s lab focuses on the genetic and molecular dissection of late endocytic trafficking. The lab uses the Drosophila compound eye as a model system to identify mutations altering membrane traffic from the cell surface to different organelles. One class of genes, exemplified by deep orange and carnation, is necessary for the delivery of cargo to lysosomes and pigment granules.
The hook gene represents a second class of mutations necessary for normal lysosomal delivery. Hook proteins are a novel family of microtubule-binding proteins that play a role in the positioning of different organelles. To investigate the molecular mechanisms by which these proteins effect membrane trafficking we are combining genetic and cell biological approaches in Drosophila and mammalian cells.
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Recent Publications Top
Primary Research Articles
Krämer, H. and Phistry, M. (1996). Mutations in the Drosophila hook gene inhibit endocytosis of the Boss transmembrane ligand into multivesicular bodies. J. Cell Biology 133, 1205-1216.
Sevrioukov, E., Walenta, J., Sunio, A., Phistry, M., and Krämer H. (1998). Oligomerization of the extracellular domain of Boss enhances its binding to the Sevenless receptor and its antagonistic effect on R7 induction. J. Cell Science 111, 737-747.
Lloyd, V., Ramaswami, M. and Krämer, H. (1998) Not just pretty eyes: Drosophila eye color mutations and lysosomal delivery. Trends in Cell Biology 8, 257-259.
Krämer, H. and Phistry, M. (1999). Genetic analysis of hook, a gene required for endocytic trafficking in Drosophila. Genetics 151, 675-684.
Sunio, A., Metcalf, A. and Krämer, H. (1999). Genetic dissection of endocytic trafficking in Drosophila using a horseradish peroxidase-bride of sevenless chimera: hook is required for normal maturation of multivesicular endosomes. Mol. Biol. Cell 10, 847-859.
Sevrioukov, E., He, J.-P., Sunio, A, Moghrabi N. and Krämer H. (1999). A role for the deep orange and carnation eye-color genes in lysosomal delivery in Drosophila. Molecular Cell 4, 479-486.
Narayanan, R., Krämer, H. and Ramaswami, M. (2000) Drosophila endosomal proteins Deep Orange and Hook regulate synapse size but not synaptic vesicle recycling. J. of Neurobiology 45,105-119.
Krämer, H. (2000) The ups and downs of life in an epithelium.J. Cell Biol. 15, F15-18.
Huizing, M. Didier, A. Walenta, J. Anikster Y., Gahl, W.A. and Krämer, H. (2001) Molecular cloning and characterization of human VPS18, VPS11, VPS16 and VPS33. Gene 264, 41-247.
Walenta, J., Didier, A., Liu, X. and Krämer, H. (2001). The Golgi-Associated Hook3 Protein is a Member of a Novel Family of Microtubule-Binding Proteins. J. Cell Biol. 152, 923-934.
Krämer, H. (2002) Sorting out signals in fly endosomes. Traffic, 3, 87-91.
Shotland, Y, Krämer H., and Eduardo A. Groisman (2003) The Salmonella SpiC protein targets the mammalian Hook3 protein to alter cellular trafficking. Mol. Microbiology 49, 1565-1576.
Sevrioukov, E., Moghrabi N. Kuhn, M. and Krämer H. (2005) A mutation in dVps28 reveals a link between ESCRT-I complex function and the actin cytoskeleton in Drosophila. Mol. Biol. Cell 16, 2301-2312.
Pulipparacharuvil, S., Akbar, A. Ray, S., Sevrioukov, E.A., Haberman A.S. and Krämer H. (2005) Drosophila Vps16A is required for trafficking to lysosomes and pigment granules biogenesis J. Cell Science 15, 3663-73
Current Lab Staff Top
Rooms NA4.202
Telephone: 214-648-1864
Adam Haberman Adam.Haberman@utsouthwestern.edu
Ali Akbar Md. Mohammed.Akbar@UTSouthwestern.edu
Sanchali Ray Sanchali.Ray@UTSouthwestern.edu
Past Lab Members
