Fyrst H, Knudsen J, Schott M A, Lubin B H, Kuypers F A
Children's Hospital Oakland Research Institute, CA 94609.
Biochem J. 1995 Mar 15;306 ( Pt 3)(Pt 3):793-9. doi: 10.1042/bj3060793.
Acyl-CoA-binding protein (ACBP) has been identified in a number of tissues and shown to affect the intracellular distribution and utilization of acyl-CoA. We have detected ACBP in the cytosol but not the membrane of human red blood cells and, using an e.l.i.s.a. with antibodies prepared against human liver ACBP, found that its concentration was 0.5 microM. To investigate the role of ACBP in human red blood cells, we added purified human liver ACBP and radiolabelled acyl-CoA to isolated membranes from these cells. ACBP prevented high concentrations of acyl-CoA from binding to the membrane but could not keep the acyl-CoA in the aqueous phase at low concentrations. This suggested the presence of a pool in the membrane with a binding affinity for acyl-CoA that was greater than that of ACBP for acyl-CoA. In the presence of lysophospholipid, this membrane-bound pool of acyl-CoA was rapidly used as a substrate by acyl-CoA:lysophospholipid acyltransferase (LAT) to generate phospholipid from lysophospholipid. We also found that ACBP-bound acyl-CoA was preferred over free acyl-CoA as a substrate by LAT. These results are the first documentation that human red blood cells contain ACBP and that this protein can affect the utilization of acyl-CoA in plasma membranes of these cells. The interactions between acyl-CoA, ACBP and the membrane suggest that there are several pools of acyl-CoA in the human red blood cell and that ACBP may have a role in regulating their distribution and fate.
酰基辅酶A结合蛋白（ACBP）已在多种组织中被鉴定出来，并被证明会影响酰基辅酶A的细胞内分布和利用。我们在人红细胞的胞质溶胶中检测到了ACBP，但在细胞膜中未检测到。使用针对人肝脏ACBP制备的抗体进行酶联免疫吸附测定（ELISA），我们发现其浓度为0.5微摩尔。为了研究ACBP在人红细胞中的作用，我们将纯化的人肝脏ACBP和放射性标记的酰基辅酶A添加到从这些细胞中分离出的膜中。ACBP可防止高浓度的酰基辅酶A与膜结合，但在低浓度下无法使酰基辅酶A保持在水相中。这表明膜中存在一个对酰基辅酶A具有比ACBP对酰基辅酶A更高结合亲和力的池。在溶血磷脂存在的情况下，这个与膜结合的酰基辅酶A池被酰基辅酶A：溶血磷脂酰基转移酶（LAT）迅速用作底物，从溶血磷脂生成磷脂。我们还发现，LAT更倾向于将与ACBP结合的酰基辅酶A而非游离酰基辅酶A用作底物。这些结果首次证明人红细胞含有ACBP，并且这种蛋白质可以影响这些细胞的质膜中酰基辅酶A的利用。酰基辅酶A、ACBP与膜之间的相互作用表明，人红细胞中存在几个酰基辅酶A池，并且ACBP可能在调节它们的分布和去向方面发挥作用。
