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Modulation of 1,25-dihydroxyvitamin D3 receptor by phospholipids and fatty acids.

1984; Elsevier BV; Volume: 25; Issue: 12 Linguagem: Inglês

10.1016/s0022-2275(20)34445-x

1539-7262

Tongyan Chen, J P Mullen, N Meglin,

Vitamin K Research Studies

The structural relationship between several lipids and their respective capacities to inhibit the specific binding of ['H]-1,25 (OH), vitamin DS to chick intestinal cytosol preparations was investigated.The lipids investigated were: a) synthetic 3-sn-phosphatidylcholines and 3-sn-phosphatidic acid, b) egg yolk 3-sn-phosphatidylcholine and its corresponding phosphatidic acid, and c) free unsaturated fatty acids and their esters.The results indicate that at least three structural elements in the phospholipid molecule appear to be important; these are: I) the structure of the fatty acid, 2) the anionic properties of the phospholipid phosphate group, and 3) the glycerol phosphate portion of the molecule.Our data also demonstrate that the position (1 or 2) and the amount (single vs. double) of unsaturated fatty acids in the phospholipid molecule do not play a major role in the receptor-1,25 (OH):!vitamin DS interaction.Furthermore, under equilibrium conditions, kinetic and Scatchard analysis suggest that phospholipids or free fatty acids may bind at a site different from the 1,25 (OH):!vitamin Abbreviations: 1,25 (OH)* DJ, 1,25dihydroxyvitamin DS; DTT, dithiothreitol; PC, 3-sn-phosphatidylcholine; PA, 3-sn-phosphatidic acid; KKD, 50 mM K~HPO,KH~PO, buffer, pH 7.4, 100 mM KCI, and 1 mM DTT; K d , equilibrium dissociation constant; Ki, the concentration for 50% maximum inhibition.