Purification and characterization of chicken lipoprotein receptor

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(I) Chylomicron remnant and VLDL remnant in chickens were prepared by the method using ultracentrifugation (d<1.019) following an in vitro incubation of chylomicron or VLDL prepared from chicken plasma with chicken LPL for 2h at 37ﾟC.(2) The chylomicron remnants and VLDL remnants yielded the almost single peak in the elution pattern on Bio-Gel A50m column (1.6 * 50cm) and the particle size were smaller than chylomicron and VLDL since the elution of remnants by Bio-Gel A50m was similar to LDL rather than chylomicron and VLDL.Chicken remnants had low triglyceride contents with high cholesterol and almost comparable Apo B100 and Apo A-I contents while lower Apo C,Apo 52kDa and Apo 20kDa contents compared to chylomicron or VLDL.(3) ^<125>I-labeled LDL,chylomicron remnant and VLDL remnant bound specificity to chicken or rat liver membranes. The specific binding of chicken ^<I25>I-labeled LDL to chicken liver membrane was inhibited by >70% with chylomicron, VLDL,VLDL remnant or LDL,while the addition of chylomicron remnant had little effect. These results demonstrate that chicken chylomicron remnant bind the site of different receptor of LDL.(4) The uptake of Chicken ^<I25>I-labeled lipoproteins to chicken primary hepatocyte was decreased to about>30% by an excess of the corresponding lipoproteins. It is concluded that the uptake of chicken lipoproteins are mediated by lipoprotein receptors.(5) In ligand blot aunalysis of chicken hepatic lipoprotein receptors, three difrerent receptor proteins (145,115 and 105 kDa) were present in chicken liver.(6) Two kinds of chicken hepatic lipoprotein receptors were purifed by a procedure with three chromatography step on Hydroxyapatite, LDL-affinity and Mono Q.The receptors (chicken hepatic apo B receptor (CHBR) -1 and CHBR-2) were characterized a molecular weight of 115kDa and 105kDa, as estimated on SDS-PAGE.On ligand blotting, both CHBR-1 and CHBR-2 bound to apo B lipoproteins.