The transport of lipophilic materials through aqueous plasma in animals is accomplished by serum lipoproteins. The critical role of lipoproteins in mediating a balance between physiological lipid transport needs and hyperlipidemic disease is well established. However, a better understanding of the physical basis of lipid transport via lipoproteins is needed. In insects, a single lipoprotein, lipophorin, functions as the major lipid transport vehicle. This lipoprotein undergoes remarkable transitions during the life cycle to meet the changing physiological needs. A specific hormone induced lipophorin transition from high to low density provides a model system for physical studies of lipoprotein metabolism in general. The metabolic events surrounding lipid loading and apoprotein association together with the interaction of lipophorin with a specific flight muscle lipase will be examined in pursuit of the following specific aims: 1. Time course and sequence of low density lipophorin formation 2. Mechanism of diacylglycerol transfer from fat body tissue to lipophorin 3. Interaction of low density lipophorin with flight muscle 4. Role of apolipophorin III as a recognition signal/activator for low density lipophorin lipase. Due to the relative simplicity of this insect system, a detailed understanding of lipoprotein metabolism is possible. The data obtained should provide basic information about lipoprotein metabolism in general that should relate to higher animals.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL034786-03
Application #
3348130
Study Section
Tropical Medicine and Parasitology Study Section (TMP)
Project Start
1985-09-30
Project End
1988-09-29
Budget Start
1987-09-30
Budget End
1988-09-29
Support Year
3
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Arizona
Department
Type
Schools of Medicine
DUNS #
City
Tucson
State
AZ
Country
United States
Zip Code
85722
Blacklock, B J; Ryan, R O (1994) Hemolymph lipid transport. Insect Biochem Mol Biol 24:855-73
Zhang, Y; Lewis, R N; McElhaney, R N et al. (1993) Calorimetric and spectroscopic studies of the interaction of Manduca sexta apolipophorin III with zwitterionic, anionic, and nonionic lipids. Biochemistry 32:3942-52
Ryan, R O; Oikawa, K; Kay, C M (1993) Conformational, thermodynamic, and stability properties of Manduca sexta apolipophorin III. J Biol Chem 268:1525-30
Singh, T K; Scraba, D G; Ryan, R O (1992) Conversion of human low density lipoprotein into a very low density lipoprotein-like particle in vitro. J Biol Chem 267:9275-80
Blacklock, B J; Smillie, M; Ryan, R O (1992) Insect lipid transfer particle can facilitate net vectorial lipid transfer via a carrier-mediated mechanism. J Biol Chem 267:14033-7
Wang, J; Liu, H; Sykes, B D et al. (1992) 31P-NMR study of the phospholipid moiety of lipophorin subspecies. Biochemistry 31:8706-12
Price, H M; Ryan, R O; Haunerland, N H (1992) Primary structure of locust flight muscle fatty acid binding protein. Arch Biochem Biophys 297:285-90
Singh, T K; Blacklock, B J; Wientzek, M et al. (1992) A turbidimetric assay of lipid transfer activity. Anal Biochem 206:137-41
Ryan, R O; Kay, C M; Oikawa, K et al. (1992) Effect of particle lipid content on the structure of insect lipophorins. J Lipid Res 33:55-63
Liu, H; Ryan, R O (1991) Role of lipid transfer particle in transformation of lipophorin in insect oocytes. Biochim Biophys Acta 1085:112-8

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