Phospholipid transfer proteins catalyze the translocation of phospholipid molecules between natural and/or artificial membranes. A major class of these proteins exhibits specificity toward phosphatidylinositol and, to a lesser extent, phosphatidylcholine and is designated phosphatidylinositol transfer protein. A critical step in the catalytic mechanism is the formation of a complex between the transfer protein and a membrane surface, at which point protein-bound and membrane-bound phospholipid is exchanged. This research program is designed to further our understanding of phosphatidylinositol transfer proteins present in bovine and rat tissues. Efforts will be made to define the substrate binding domain of the transfer protein in terms of phospholipid-protein stoichiometry and fatty acyl chain specificity among a series of natural and synthetic phosphatidylinositols and phosphatidylcholines. Using polyclonal antibody raised against rat phosphatidylinositol transfer protein, the level and activity of transfer protein in gross anatomical regions of rat brain are quantitated and compared with the activities of important enzymes in the synthesis of phosphatidylinositol and phosphatidylcholine. Similar measurements are carried out with isolated neuronal, astroglial, and oligodendroglial cells. Changes in these activities as a function of central nervous system development are described. In addition, correlations between stimulated phosphoinositide metabolism and transfer protein levels and activity are made. Another specific goal is the isolation and characterization of the gene for rat phosphatidylinositol transfer protein. This phase of the research will yield not only a means of directing the synthesis of the protein in a suitable bacterial host and providing larger quantities of the protein for physical and chemical studies, but also information on the DNA and protein sequences which will lead to future investigations on the genetic regulation and catalytic mechanism of phosphatidylinositol transfer protein.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM024035-10
Application #
3272035
Study Section
Physiological Chemistry Study Section (PC)
Project Start
1977-07-01
Project End
1989-08-31
Budget Start
1986-09-01
Budget End
1987-08-31
Support Year
10
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of Kansas
Department
Type
Schools of Medicine
DUNS #
016060860
City
Kansas City
State
KS
Country
United States
Zip Code
66160
Li, Hong; Tremblay, Jacqueline M; Yarbrough, Lynwood R et al. (2002) Both isoforms of mammalian phosphatidylinositol transfer protein are capable of binding and transporting sphingomyelin. Biochim Biophys Acta 1580:67-76
Yoder, M D; Thomas, L M; Tremblay, J M et al. (2001) Structure of a multifunctional protein. Mammalian phosphatidylinositol transfer protein complexed with phosphatidylcholine. J Biol Chem 276:9246-52
Tremblay, J M; Li, H; Yarbrough, L R et al. (2001) Modifications of cysteine residues in the solution and membrane-associated conformations of phosphatidylinositol transfer protein have differential effects on lipid transfer activity. Biochemistry 40:9151-8
Tremblay, J M; Voziyan, P A; Helmkamp Jr, G M et al. (1998) The C-terminus of phosphatidylinositol transfer protein modulates membrane interactions and transfer activity but not phospholipid binding. Biochim Biophys Acta 1389:91-100
Voziyan, P A; Tremblay, J M; Yarbrough, L R et al. (1997) Importance of phospholipid in the folding and conformation of phosphatidylinositol transfer protein: comparison of apo and holo species. Biochemistry 36:10082-8
Voziyan, P A; Tremblay, J M; Yarbrough, L R et al. (1996) Truncations of the C-terminus have different effects on the conformation and activity of phosphatidylinositol transfer protein. Biochemistry 35:12526-31
Tremblay, J M; Helmkamp, G M; Yarbrough, L R (1996) Limited proteolysis of rat phosphatidylinositol transfer protein by trypsin cleaves the C terminus, enhances binding to lipid vesicles, and reduces phospholipid transfer activity. J Biol Chem 271:21075-80
Dickeson, S K; Helmkamp Jr, G M; Yarbrough, L R (1994) Sequence of a human cDNA encoding phosphatidylinositol transfer protein and occurrence of a related sequence in widely divergent eukaryotes. Gene 142:301-5
Borror, C A; Helmkamp Jr, G M (1991) Transport of phosphatidylinositol to rat hepatocyte plasma membrane catalyzed by phosphatidylinositol transfer protein. Biochim Biophys Acta 1068:52-60
Khan, Z U; Helmkamp Jr, G M (1990) Stimulation of cholinephosphotransferase activity by phosphatidylcholine transfer protein. Regulation of membrane phospholipid synthesis by a cytosolic protein. J Biol Chem 265:700-5

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