Assistant Professor of Biochemistry and Molecular Biology Adjunct Cellular Biology Ph.D. Office: 3034 CCRC Contact Phone Number: 583-5550 Lab: 3038 CCRC Lab Phone: 583-5551 E-mail: rsteet@ccrc.uga.edu

Research Interests

My laboratory studies human disorders that involve abnormal synthesis or disposal of glycoproteins. We are currently investigating the pathogenic mechanisms that underlie mucolipidosis II, a lysosomal storage disorder characterized by defects in mannose 6-phosphate biosynthesis, using zebrafish as a model system. In particular, we are interested in understanding how impaired mannose 6-phosphate biosynthesis impacts extracellular matrix deposition and growth factor regulation. Our research efforts also include the identification and characterization of novel glycosylation disorders that arise from defects in vesicle trafficking proteins. With the aid of high-resolution confocal imaging techniques, we are conducting experiments in cultured cells aimed at elucidating the dynamic interplay between Golgi membrane trafficking and protein glycosylation.

Selected Recent Publications

• Steet, R., Chung, S., Pine, C., Do, H., Kornfeld, S., (2007) Selective Action of the Iminosugar Isofagomine, a Pharmacological Chaperone For Mutant Forms of Acid-ß-Glucosidase, Biochemical Pharmacology, 73(9): 1376-83.
  
  
• Steet, R., Chung, S., Wustman, B., Powe, A., Do, H., Kornfeld, S., (2006) The Iminosugar Isofagomine Increases the Activity of N370S Mutant Acid-ß-Glucosidase in Gaucher Fibroblasts By Several Mechanisms, Proceedings of the National Academy of Sciences, 103(37): 13813-13818.
  
  
• Steet, R. and Kornfeld, S. (2006) COG-7 Deficient Human Fibroblasts Exhibit Altered Recycling of Golgi Proteins, Mol. Biol. Cell, 17: 2312-2321.
   
  
• Spaapen, L.J.M., Bakker, J.A., van der Meer, S.B., Sijstermans, H.J., Steet, R., Wevers, R.A., Jaeken, J. (2005) Clinical and biochemical presentation of siblings with COG-7 deficiency, a lethal multiple O- and N-glycosylation disorder. J. Inherit. Metab. Dis. 28: 707-714.
   
  
• Steet, R., Lee, W.S., Kornfeld, S. (2005) Identification of the Minimal Lysosomal Enzyme Recognition Domain in Cathepsin D.  J. Biol. Chem. 280(39): 33318-23
  
  
• Steet, R., Hullin, R., Kudo, M., Martinelli M., Bosshard, N.U., Schaffner, T., Kornfeld, S., Steinmann, B. (2005) A Splicing Mutation in the a/ß GlcNAc-1-Phosphotransferase Gene Results in an Adult Onset Form of Mucolipidosis III Associated with Sensory Neuropathy and Cardiomyopathy. Am J Med Genet. 132(4): 369-75.
   
  
• Wu, X., Steet, R., Bohorov, O., Bakker, J., Newell, J., Krieger, M., Spaapen, L., Kornfeld, S., Freeze, H.H. (2004) Mutation of the COG complex subunit gene COG7 causes a lethal congenital disorder. Nat. Med.  10(5), 518-23
  
  
• Steet, R., Melançon, P. and Kuchta, R.D.  (2000) 3’-Azidothymidine potently inhibits the biosynthesis of highly branched N-linked oligosaccharides and poly-N-acetyllactosamine chains in cells. J. Biol. Chem. 275(35), 26812-20
  
  
• Steet, R., Alizadeh, M., Melançon, P. and Kuchta, R.D.  (1999)  3’-Azidothymidine significantly alters glycosphingolipid synthesis in melanoma cells and decreases the shedding of gangliosides.  Glycoconj J. 16(3), 237-45