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Charles J. Waechter
Professor
B.S. University of Maryland
Ph.D. University of Kentucky College of Medicine
waechte@uky.edu
859-323-6352

Research Interests  |  Publications  |  PubMed

Research Interests:

This laboratory is interested in the role of isoprenoid intermediates in the N-glycosylation and isoprenylation of proteins in mammalian cells. Protein N-glycosylation is required for the proper assembly, correct intracellular routing and function of voltage-sensitive sodium-channels, the insulin receptor, and many other membrane glycoproteins mediating important cellular functions. In this multi-stage assembly process, a glucosylated precursor oligosaccharide is synthesized while attached to the long-chain (C95) polyisoprenyl phosphate carrier, dolichyl phosphate (Dol-P). In the current model of the assembly process, three dolichylphosphosaccharide intermediates "flip-flop" from the cytoplasmic monolayer, where they are synthesized, to the lumenal monolayer, where they participate in the completion of Oligo-P-P-Dol synthesis. Current studies are aimed at determining how many enzymes are involved in the pathway for Dol-P biosynthesis, and how they are regulated. A second objective is to determine if membrane proteins mediate the transbilayer movement of dolichylphosphosaccharide intermediates from the cytoplasmic monolayer to the lumenal leaflet of the RER. Recently, in collaboration with Doug Andres, we have also discovered that free farnesol and geranylgeraniol are utilized for the isoprenylation of regulatory proteins like Ras and Rab, presumably after being converted to farnesyl pyrophosphate and geranylgeranyl pyrophosphate. Current studies are aimed at elucidating the enzymatic mechanism by which the isoprenols are converted to the allylic pyrophosphate intermediates or novel isoprenyl donors.

Click here for image describing the Role of Hypothetical Flippases in Transbilayer Movement of Lipid Intermediates in RER.

Representative Publications:

Crick, D. C., Andres, D. A., Danesi, R., Macchia, M., and Charles J. Waechter "Geranylgeraniol Overcomes the Block of Cell Proliferation by Lovastatin in C6 Glioma Cells", J. Neurochem. 70, 2397-2405 1998).

Wolucka, B. A., Rush, J. S>, Waechter, C. J., Shibaev, V. N., and de Hoffman, E.  (1998) "An Electrospray-Ionization Tandem Mass Spectrometry Method for Determination of the anomeric Configuration of Glycosyl 1-Phosphate Derivatives: Anal. Biochem 255, 244-251.

Frank, D. W., and Waechter, C. J. (1998) "Purification and Characterization of a Polyisoprenyl Phosphate Phosphatase from Pig Brain: Possible Dual Specificity" J. Biol. Chem. 273, 11791-11798.

Rush, J. S., van Leyen, K., Ouerfelli, O., Wolucka, B. and Waechter, C. J. (1998) "Transbilayer Movement of Glc-P-Dolichol and its Function as a Glucosyl Donor:  Protein-Mediated Transport of a Water-Soluble Analog into Sealed ER Vesicles form Pig Brain" Glycobiology 8, 1195-1205.

Rush, J. S., and Waechter, C. J. (1998) "Topological Studies on the Enzymes Catalyzing the Biosynthesis of Glc-P-Dolichol and the Triglucosyl Cap of Glc₃Man₉GlcNAc₂-P-P-Dolichol in Microsomal Vesicles from Pig Brain: Use of the Processing Glucosidases I/II as Latency Markers" Glycobiology 8, 1207-1213.

Faulkner, A., Chen, X., Rush, J., Horazdovsky, Waechter, C. J., Carman, G. M., and Sternweiss, P. C. (1999) "The LPP1 and DPP1 Gene Products Account for Most of the Isoprenoid Phosphate Phosphatase Activities in Saccharomyces cerevisiae: J. Biol. Chem. 274, 14831-14837.

Thai, L., Rush, J. S., Maul, J. Rodgers, D. L., Chappell, J. Waechter, C. J. "Farnesol is Utilized for Isoprenoid Biosynthesis in Plant Cells via Farenesyl Pyrophosphate formed by Successive Monophosphorylation Reactions" Proc. Natl. Acad. Sci. U.S.A. (in press).