The long term objective of this research is to develop a thorough understanding of the biosyntheis of the asparagine-linked saccharide side chains of mammalian glycoproteins. Since a large number of different enzymes are involved in the assembly of these oligosaccharides, studies must be directed to investigations on the kinetics, properties, and mechanisms of the individual glycosyltransferases. Recent results indicate that it will also be important to reconstitue some of the enzymes in a phospholipid matrix and investigate the properties of the enzyme/phospholipid complexes. The work proposed will therefor involve a comprehensive investigation of a number of the glycosyltranferases catalyzing synthesis of the glycosidic linkages found in glycoproteins. Specific assays will be developed for the enzymes, and the transferases will be solubilized, at least partialyy purified, and characterized. Investigations will them be directed at understanding how the glycoytransferases act in concert to direct the synthesis of specific oligosaccharide structures that are found on mammalian glycoproteins. In addition, this research will also be directed to studies of the effects of dolichols on the physical properties of membranes. More specifically, the objectives of th proposed research are to: a) Solubilize and purify membrane-bound glycosyltransferases present in microsomes prepared from rabbit liver and other mammalian tissues. b) Characterize the purified glycosyltranferases in regard to mechanism, specificity, and physical glycosyltransferases in regard to mechanism, specificity, and physical and kinetic properties. c) Reconstitue the enzymes in a phospholipid matrix and investigate the effects of the phospholipids enzyme properties. d) Determine the phospholipid specificity and the physical properties of the phospholipid matrix required for optimal enzyme activity, and e) Investigate the effects of dolichols on the properties of membranes including bilayer stability, permeability, and membrane fusion. Although information currently available supports a common pathway for the synthesis of all asparagine-linked oligosaccarides, additinal research is required to fully understand glycoprotein biosynthesis.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA016777-13
Application #
3164508
Study Section
Pathobiochemistry Study Section (PBC)
Project Start
1977-09-01
Project End
1990-12-31
Budget Start
1987-01-01
Budget End
1987-12-31
Support Year
13
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Alabama Birmingham
Department
Type
School of Medicine & Dentistry
DUNS #
004514360
City
Birmingham
State
AL
Country
United States
Zip Code
35294
Schutzbach, John S (2006) Assay of dolichyl-phospho-mannose synthase reconstituted in a lipid matrix. Methods Mol Biol 347:31-41
Schutzbach, J S; Zimmerman, J W (1992) Yeast dolichyl-phosphomannose synthase: reconstitution of enzyme activity with phospholipids. Biochem Cell Biol 70:460-5
Schutzbach, J S; Forsee, W T (1990) Calcium ion activation of rabbit liver alpha 1,2-mannosidase. J Biol Chem 265:2546-9
Schutzbach, J S; Jensen, J W (1989) Bilayer membrane destabilization induced by dolichylphosphate. Chem Phys Lipids 51:213-8
Forsee, W T; Palmer, C F; Schutzbach, J S (1989) Purification and characterization of an alpha-1,2-mannosidase involved in processing asparagine-linked oligosaccharides. J Biol Chem 264:3869-76
Jensen, J W; Schutzbach, J S (1989) Phospholipase-induced modulation of dolichyl-phosphomannose synthase activity. Biochemistry 28:851-5
Jensen, J W; Schutzbach, J S (1988) Modulation of dolichyl-phosphomannose synthase activity by changes in the lipid environment of the enzyme. Biochemistry 27:6315-20
Monti, J A; Christian, S T; Schutzbach, J S (1987) Effects of dolichol on membrane permeability. Biochim Biophys Acta 905:133-42
Lai, C S; Schutzbach, J S (1986) Localization of dolichols in phospholipid membranes. An ESR spin label study. FEBS Lett 203:153-6
Jensen, J W; Schutzbach, J S (1985) Activation of dolichyl-phospho-mannose synthase by phospholipids. Eur J Biochem 153:41-8