Itoh K, Morimoto S, Shiraishi T, Taniguchi K, Onishi T, Kumahara Y
Department of Medicine and Geriatrics, Osaka University Medical School, Japan.
Biochem Biophys Res Commun. 1988 Jun 30;153(3):1315-23. doi: 10.1016/s0006-291x(88)81372-x.
Studies were made on the direct effect of platelet-derived growth factor (PDGF) on the high-affinity (Ca2+ +Mg2+)-ATPase, a membrane bound Ca2+-extrusion pump enzyme of the basolateral membranes (BLM) of canine kidney (Km for free Ca2+ = 1.0 x 10(-7) M, Vmax = 180 nmol Pi/mg/min). At 1 x 10(-7) M free Ca2+, PDGF (10(-10)-10(-8) M) stimulated the enzyme activity significantly. Addition of 5 - 200 microM suramin, a compound that blocks binding of PDGF to its receptors on cell membranes, inhibited the stimulatory effect of PDGF dose-dependently (IC50 = 40 microM). A high affinity specific receptor for PDGF (Kd = 4.4 x 10(-10) M, Bmax = 460 fmol/mg protein) was detected on BLM preparations by radioreceptor assay with 125I-PDGF and unlabelled PDGF. Suramin (10-1000 microM) also inhibited the binding of PDGF to BLM preparations dose-dependently. From these results, it is proposed that PDGF stimulates (Ca2+ +Mg2+)-ATPase activity of kidney BLM preparations by enhancing its affinity for free Ca2+ through a specific receptor.
开展了关于血小板衍生生长因子（PDGF）对高亲和力（Ca2+ +Mg2+）-ATP酶直接作用的研究，该酶是犬肾基底外侧膜（BLM）的一种膜结合Ca2+ 外排泵酶（游离Ca2+ 的Km = 1.0 x 10(-7) M，Vmax = 180 nmol Pi/mg/min）。在游离Ca2+ 浓度为1 x 10(-7) M时，PDGF（10(-10)-10(-8) M）显著刺激了该酶的活性。加入5 - 200 microM的苏拉明（一种能阻断PDGF与其细胞膜上受体结合的化合物），剂量依赖性地抑制了PDGF的刺激作用（IC50 = 40 microM）。通过用125I-PDGF和未标记的PDGF进行放射受体分析，在BLM制剂上检测到了一种对PDGF具有高亲和力的特异性受体（Kd = 4.4 x 10(-10) M，Bmax = 460 fmol/mg蛋白质）。苏拉明（10 - 1000 microM）也剂量依赖性地抑制了PDGF与BLM制剂的结合。根据这些结果，提出PDGF通过特定受体增强对游离Ca2+ 的亲和力来刺激肾BLM制剂的（Ca2+ +Mg2+）-ATP酶活性。
