Two canonical binding sites for the Ets family of transcription factors have been identified within the TCR-zeta promoter. These sites bind Elf-1, and play an important role in basal transcription of zeta. Ligand-mediated TCR degradation is inhibitable both by reagents that block vesicular acidification and by inhibitors of the ubiquitin/proteasome pathway, suggesting a complex pathway leading to TCR degradation. Our determination that the TCR is a substrate for ubiquitination has led us to evaluate ubiquitination in more detail. A family of human E2 enzymes (UbcH5A-C) have been cloned and characterized. These E2s are widely expressed in human tissues and function in conjunction with the only characterized human E3, E6-AP, in the ubiquitination of proteins. We have also been studying a novel yeast E2, UBC6, a novel type IV transmembrane protein found associated with membranes of the ER. The short transmembrane domain of UBC6 is responsible for its distribution within the cells, progressive lengthening the transmembrane segment re-targets UBC6 to the Golgi Apparatus and then to the cell surface. Two murine E3 enzymes have been characterized. One of these is the murine homolog of E6-AP, the other is a protein found to have homology to E6-AP, termed Nedd-4. Like E6-AP, Nedd-4 is an E3 enzyme, both of these function with the UbcH5 family of E2s in the ubiquitination of cellular proteins. These E3s exhibit distinct subcellular localizations, E6-AP is expressed predominantly in the nucleus, Nedd-4 is present exclusively in the cytosol. Nedd-4 has two distinct E2 bindings sites, one of which binds the amino terminus of E2s and the other showing affinity solely for the carboxyl component of E2s. These data suggest models for ubiquitination involving oligomerization of E2 and E3s.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Intramural Research (Z01)
Project #
1Z01BC009392-04
Application #
2463794
Study Section
Special Emphasis Panel (LICB)
Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
1996
Total Cost
Indirect Cost
Name
National Cancer Institute Division of Basic Sciences
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Martin, Damali N; Boersma, Brenda J; Yi, Ming et al. (2009) Differences in the tumor microenvironment between African-American and European-American breast cancer patients. PLoS One 4:e4531
Das, Ranabir; Mariano, Jennifer; Tsai, Yien Che et al. (2009) Allosteric activation of E2-RING finger-mediated ubiquitylation by a structurally defined specific E2-binding region of gp78. Mol Cell 34:674-85
Kostova, Zlatka; Tsai, Yien Che; Weissman, Allan M (2007) Ubiquitin ligases, critical mediators of endoplasmic reticulum-associated degradation. Semin Cell Dev Biol 18:770-9
Brauweiler, A; Lorick, K L; Lee, J P et al. (2007) RING-dependent tumor suppression and G2/M arrest induced by the TRC8 hereditary kidney cancer gene. Oncogene 26:2263-71
Hakli, M; Lorick, K L; Weissman, A M et al. (2004) Transcriptional coregulator SNURF (RNF4) possesses ubiquitin E3 ligase activity. FEBS Lett 560:56-62
Fang, S; Weissman, A M (2004) A field guide to ubiquitylation. Cell Mol Life Sci 61:1546-61
Webster, Jack M; Tiwari, Swati; Weissman, Allan M et al. (2003) Inositol 1,4,5-trisphosphate receptor ubiquitination is mediated by mammalian Ubc7, a component of the endoplasmic reticulum-associated degradation pathway, and is inhibited by chelation of intracellular Zn2+. J Biol Chem 278:38238-46
Magnifico, Alessandra; Ettenberg, Seth; Yang, Cuihong et al. (2003) WW domain HECT E3s target Cbl RING finger E3s for proteasomal degradation. J Biol Chem 278:43169-77
Liang, Jun-Shan; Kim, Tonia; Fang, Shengyun et al. (2003) Overexpression of the tumor autocrine motility factor receptor Gp78, a ubiquitin protein ligase, results in increased ubiquitinylation and decreased secretion of apolipoprotein B100 in HepG2 cells. J Biol Chem 278:23984-8