YI ZHENG
ASSISTANT PROFESSOR



EDUCATION:
B.S. 1986, Tsinghua University, Beijing, China
M.S. 1988, Cornell University, Ithaca, New York
Ph.D. 1991, Cornell University, Ithaca, New York

RESEARCH INTERESTS: In all eukaryotic organisms, a family of monomeric 20-25 kDa GTP-binding proteins (Ras superfamily of small G-proteins) plays an essential role in linking many cell-surface receptors to intracellular effector proteins, leading to physiological responses such as cell-cell communication, cytoskeletal reorganization, and cell proliferation and differentiation. The GTP-binding/GTPase cycles of these signal transducers are key regulatory features of their biological functions: the guanine nucleotide exchange factors (GEFs) activate the G-proteins by stimulating the exchange of GDP for GTP in response to extracellular stimuli, the GTPase-activating proteins (GAPs) will then catalyze the conversion of the GTP-bound active forms of G-proteins back to their inactive GDP-bound states, and the GDP dissociation inhibitor proteins serve to stabilize the G-proteins at either state and target them to specific intracellular locations. We are particularly interested in the elucidation of the molecular mechanisms under-lying the biological functions of these GTP-binding molecular switches and the related regulatory proteins through molecular biochemical approaches. We are currently using both the in vitro mutagenesis and chimeric methods and the in vivo transfection and microinjection methods to study the cellular functions of members of the Rho-subfamily of Ras-related GTPases in an effort to delineate the structure-function relationships of these small G-proteins, their upstream activator GEFs, and their down regulator/effector GAPs.

PUBLICATIONS:
1. Zheng, Y., Shopes, B., Holowka, D., and Baird, B. (1991) Conformations of IgE bound to its receptor FceRI and in solution. Biochemistry, 30, 9125-9132.
2. Zheng, Y., Shopes, B., Holowka, D., and Baird, B. (1992) Dynamic conformations compared for IgE and IgG1 in solution and bound to receptors. Biochemistry, 31, 7446-7456.
3. Baird, B., Zheng, Y., and Holowka, D. (1993) Structural mapping of IgE-FceRI, an immuno-receptor complex. Accounts of Chemical Research, 26, 428-434.
4. Chang, E-y., Zheng, Y., Holowka, D., and Baird, B. (1995) Alteration of lipid composition modulates FceRI signaling in RBL cells. Biochemistry, 34, 4376-4384.
5. Zheng,Y., Hart, M., Shinjo, K., Evans, T., Bender, A., and Cerione, R.A. (1993) Biochemical comparisons of the Saccharomyces cerevisiae Bem2 and Bem3 proteins: Delineation of a limit Cdc42 GTPase-activating protein domain. J. Biol. Chem., 268, 24629-24634.
6. Barfod, E., Zheng, Y., Kuang, W., Hart, M., Evans, T., Cerione, R.A., and Ashkenazi, A. (1993) Cloning and expression of a human Cdc42 GTPase-activating protein reveals a functional SH3-binding domain. J. Biol. Chem., 268, 26059-26062.
7.Hart, M., Eva, A., Zangrilli, D., Aaronson, S., Evans, T., Cerione, R.A., and Zheng, Y. (1994) Cellular transformation and guanine nucleotide exchange activity are catalyzed by a common domain on the dbl oncogene product. J. Biol. Chem., 269, 62-65.
8. Zheng, Y., Cerione, R.A., and Bender, A. (1994) Control of the yeast bud-site assembly GTPase Cdc42: Catalysis of guanine nucleotide exchange by Cdc24 and stimulation of GTPase activity by Bem3. J. Biol. Chem., 269, 2369-2372.
9. Zheng, Y., Bagrodia, S., and Cerione, R.A. (1994) Activation of phosphoinositide 3-kinase activity by Cdc42Hs binding to p85. J. Biol. Chem., 269, 18727-18730.
10. Peterson, J., Zheng, Y., Bender, L., Myers, A., Cerione, R., and Bender, A. (1994) Interactions between the bud-emergence proteins Bem1p and Bem2p and Rho-type GTPases in yeast. J. Cell Biol., 127, 1395-1406.
11. Zheng, Y., Hart, M., and Cerione, R.A. (1995) Guanine nucleotide exchange catalyzed by dbl oncogene product. Methods in Enzymol., 256, 77-84.
12. Li, R., Zheng, Y., and Drubin, D.G. (1995) Regulation of membrane actin cytoskeleton assembly during polarized cell growth in budding yeast. J. Cell Biol., 128, 599-615.
13. Zheng, Y., Bender, A., and Cerione, R.A. (1995) Interactions among proteins involved in bud-site selection and bud-site assembly in Saccharomyces cerevisiae. J. Biol. Chem., 270, 626-630.
14. Cicchetti, P., Ridley, A., Zheng, Y., Cerione, R.A., and Baltimore, D. (1995) cDNA cloning and characterization of 3BP-1, an SH3 domain binding protein which has GAP activity for Rac and inhibits growth factor induced membrane ruffling in fibroblasts. The EMBO J., 14, 3127-3135.
15. Zheng, Y., Olson, M., Hall, A., Cerione, R.A., and Toksoz, D. (1995) Direct involvement of the small GTP-binding protein Rho in lbc oncogene function. J. Biol. Chem., 270, 9031-9034.