Hwang S B
Department of Biochemical Regulation, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065.
Arch Biochem Biophys. 1987 Sep;257(2):339-44. doi: 10.1016/0003-9861(87)90574-1.
The binding of 3H-labeled 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine (PAF) to isolated rat liver plasma membranes and its inhibition by PAF agonists and receptor antagonists was demonstrated. The specific binding was readily saturable with a high affinity. The equilibrium dissociation constant (KD) value was 0.51 (+/- 0.14) nM and the maximal number of binding sites (Bmax) was estimated to be 141 (+/- 18) fmol/mg protein. The binding site was PAF specific-biologically inactive enantiomer was practically inactive. Two PAF-like receptor antagonists, Ono-6240 and CV-3988, and two PAF-unlike receptor antagonists, L-652,731 and kadsurenone, also displaced the binding of [3H]PAF to rat liver plasma membranes but their relative potencies in this system differed from those found in other receptor systems. Mg2+ potentiated [3H]PAF binding but inhibited it at concentrations higher than 10 mM. Both Na+ and K+ inhibited the Mg2+-potentiated binding, an ionic effect which was different from that found in rabbit platelets. These results suggest that rat livers contain PAF-specific receptors, and the receptors in rat livers are different from those found in other receptor systems.
已证实3H标记的1-O-烷基-2-O-乙酰基-sn-甘油-3-磷酸胆碱（PAF）与分离的大鼠肝细胞膜的结合及其被PAF激动剂和受体拮抗剂的抑制作用。特异性结合易于饱和且具有高亲和力。平衡解离常数（KD）值为0.51（±0.14）nM，结合位点的最大数量（Bmax）估计为141（±18）fmol/mg蛋白质。结合位点具有PAF特异性——生物学上无活性的对映体实际上无活性。两种PAF样受体拮抗剂，Ono-6240和CV-3988，以及两种非PAF样受体拮抗剂，L-652,731和海风藤酮，也能取代[3H]PAF与大鼠肝细胞膜的结合，但它们在该系统中的相对效力与在其他受体系统中发现的不同。Mg2+增强[3H]PAF的结合，但在高于10 mM的浓度下抑制它。Na+和K+均抑制Mg2+增强的结合，这种离子效应与在兔血小板中发现的不同。这些结果表明大鼠肝脏含有PAF特异性受体，并且大鼠肝脏中的受体与在其他受体系统中发现的不同。
