Dantuma N P, Van Marrewijk W J, Wynne H J, Van der Horst D J
Department of Experimental Zoology, Utrecht University, The Netherlands.
J Lipid Res. 1996 Jun;37(6):1345-55.
A single type of high density lipoprotein (HDLp) binding sites is present at intact fat body tissue and in fat body membranes of larval and adult locusts. HDLp is bound with high affinity (Kd approximately 10(-7) M). This interaction does not require divalent cations and is heat-labile because heat-treatment of fat body membranes results in a substantial reduction of the maximal binding capacity. In addition to unlabeled HDLp and low density lipophorin (LDLp), human low density lipoprotein also seems to compete with radiolabeled HDLp for this binding site, suggesting a relaxed specificity. Induction of lipid mobilization with adipokinetic hormone did not change the binding characteristics of the fat body. An increase in the binding capacity of intact fat body tissue in the adult stage suggests that the number of cell surface binding sites is upregulated during development. However, the total number of HDLp binding sites appears to be constant, because larval and adult fat body membranes have similar binding capacities.
在幼虫和成虫蝗虫的完整脂肪体组织及脂肪体膜中存在单一类型的高密度脂蛋白（HDLp）结合位点。HDLp以高亲和力（解离常数Kd约为10⁻⁷M）结合。这种相互作用不需要二价阳离子，并且对热不稳定，因为对脂肪体膜进行热处理会导致最大结合能力大幅降低。除了未标记的HDLp和低密度脂蛋白（LDLp）外，人低密度脂蛋白似乎也与放射性标记的HDLp竞争该结合位点，这表明其特异性较为宽松。用脂肪动激素诱导脂质动员并未改变脂肪体的结合特性。成年期完整脂肪体组织结合能力的增加表明，在发育过程中细胞表面结合位点的数量上调。然而，HDLp结合位点的总数似乎是恒定的，因为幼虫和成虫的脂肪体膜具有相似的结合能力。
