Stevens M D, DiSilvestro R A, Harris E D
Biochemistry. 1984 Jan 17;23(2):261-6. doi: 10.1021/bi00297a014.
Membrane fragments from aortic and heart tissues of immature chicks were observed to bind highly purified, 125I-labeled chick ceruloplasmin. The binding reaction exhibited a linear Scatchard plot for both tissues and showed for each an apparent dissociation constant (Kd) of about 10(-8) M. On the basis of Scatchard analyses, aorta contained 1.5 pmol of receptors/mg of membrane protein, whereas receptors in the membranes from heart tissue were at least 5 times more dense. The binding of chick ceruloplasmin to aorta membranes was trypsin sensitive and neuraminidase insensitive, and showed both saturation and reversibility. Various sialoglycoproteins in 500 molar excess had very little effect on the binding. The asialo derivatives of these proteins likewise did not inhibit the binding. Human ceruloplasmin was found to bind very weakly to the chick membranes. Asialo chick ceruloplasmin bound with the same efficacy as native chick ceruloplasmin. Heat-denatured chick ceruloplasmin, however, was very ineffectual in displacing native 125I-ceruloplasmin from the membranes. These studies provide the first evidence for a homologous membrane receptor for native ceruloplasmin in the plasma membranes of animal cells.
观察到来自未成熟雏鸡主动脉和心脏组织的膜片段能结合高度纯化的、125I标记的鸡血浆铜蓝蛋白。两种组织的结合反应均呈现线性Scatchard图，且每种组织的表观解离常数（Kd）约为10^(-8)M。基于Scatchard分析，主动脉每毫克膜蛋白含1.5皮摩尔受体，而心脏组织膜中的受体密度至少高5倍。鸡血浆铜蓝蛋白与主动脉膜的结合对胰蛋白酶敏感，对神经氨酸酶不敏感，且具有饱和性和可逆性。500摩尔过量的各种唾液酸糖蛋白对结合的影响很小。这些蛋白的去唾液酸衍生物同样不抑制结合。发现人血浆铜蓝蛋白与鸡膜的结合非常弱。去唾液酸鸡血浆铜蓝蛋白与天然鸡血浆铜蓝蛋白的结合效果相同。然而，热变性鸡血浆铜蓝蛋白在从膜上置换天然125I-血浆铜蓝蛋白方面非常无效。这些研究为动物细胞质膜中天然血浆铜蓝蛋白的同源膜受体提供了首个证据。
