The overall objective of this proposal is to study the molecular mechanisms involved in the process of endocytosis. Our approach is to isolate and characterize animal cell mutants that are deficient in endocytic function. Moreover, we focus specifically on mutants that carry conditional-lethal defects. The agents that we use to isolate the mutants are highly potent protein toxins that require endocytic functions to express their lethal activities.
Our specific aims are three-fold: 1. Further studies on G.7.1, a Chinese hamster ovary cell mutant carrying a conditional-lethal defect in endocytic function: We have so far isolated two mutants that at elevated temperature (39.5 C) lose viability and in the process become resistant to protein toxins. We have studied one of these mutants, called G.7.1, in more detail and the results suggest that it contains a heat-sensitive lesion affecting vacuolar acidification. We propose to more precisely identify the lesion in this mutant and to use the mutant as a model to investigate what effect the lesion has on endocytic processes. 2. Isolation and characterization of more mutants: Our selection procedure is capable of rescuing many different kinds of mutants containing conditional-lethal defects in endocytic function. We propose to search for, and characterize, additional mutants. 3. Genetic characterization of mutants: With techniques of somatic cell genetics we will determine whether the lesions in our mutants are expressed dominantly or recessively. Mutants that contain recessive lesions will be classified into complementation groups. We also propose to isolate and characterize revertants of the mutants.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM034297-03
Application #
3285029
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Project Start
1985-01-01
Project End
1989-12-31
Budget Start
1987-01-01
Budget End
1987-12-31
Support Year
3
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Texas-Dallas
Department
Type
Schools of Arts and Sciences
DUNS #
City
Richardson
State
TX
Country
United States
Zip Code
75080
Chen, Alice; AbuJarour, Ramzey J; Draper, Rockford K (2003) Evidence that the transport of ricin to the cytoplasm is independent of both Rab6A and COPI. J Cell Sci 116:3503-10
Chen, Alice; Hu, Tonghuan; Mikoryak, Carole et al. (2002) Retrograde transport of protein toxins under conditions of COPI dysfunction. Biochim Biophys Acta 1589:124-39
Draper, R K; Hudson, R T; Hu, T (2001) Use of aminoglycoside antibiotics and related compounds to study ADP-ribosylation factor (ARF)/coatomer function in Golgi traffic. Methods Enzymol 329:372-9
Hu, T; Kao, C Y; Hudson, R T et al. (1999) Inhibition of secretion by 1,3-Cyclohexanebis(methylamine), a dibasic compound that interferes with coatomer function. Mol Biol Cell 10:921-33
Hudson, R T; Draper, R K (1997) Interaction of coatomer with aminoglycoside antibiotics: evidence that coatomer has at least two dilysine binding sites. Mol Biol Cell 8:1901-10
Corboy, M J; Draper, R K (1997) Elevation of vacuolar pH inhibits the cytotoxic activity of furin-cleaved exotoxin A. Infect Immun 65:2240-2
Kao, C Y; Draper, R K (1992) Retention of secretory proteins in an intermediate compartment and disappearance of the Golgi complex in an END4 mutant of Chinese hamster ovary cells. J Cell Biol 117:701-15
Wang, R H; Colbaugh, P A; Kuo, P et al. (1992) Novel method for isolating mammalian cells defective in fluid-phase endocytosis. Somat Cell Mol Genet 18:543-51
Park, J E; Draper, R K; Brown, W J (1991) Biosynthesis of lysosomal enzymes in cells of the End3 complementation group conditionally defective in endosomal acidification. Somat Cell Mol Genet 17:137-50
Draper, R K; Goda, Y; Brodsky, F M et al. (1990) Antibodies to clathrin inhibit endocytosis but not recycling to the trans Golgi network in vitro. Science 248:1539-41

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