EVIDENCE FOR BINDING OF HUMAN-PREGNANCY ZONE PROTEIN PROTEINASE COMPLEX TO ALPHA-2-MACROGLOBULIN RECEPTORS
EVIDENCE FOR BINDING OF HUMAN-PREGNANCY ZONE PROTEIN PROTEINASE COMPLEX TO ALPHA-2-MACROGLOBULIN RECEPTORS
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DOI：
10.1016/0304-4165(86)90276-x
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发表时间：
1986-10-01
期刊：
影响因子：
--
通讯作者：
SONNE, O
中科院分区：
文献类型：
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作者：
GLIEMANN, J;MOESTRUP, S;SONNE, O
125i标记的人妊娠带蛋白与胰凝乳酶复合物在大鼠静脉注射后半周期2.3 min从循环中去除。6分钟后，雄性和雌性妊娠大鼠的肝脏中约有67%的标签存在，脾脏中约有3%。原生孕带蛋白半数去除时间大于30 min。其他器官的吸收，包括胎盘和胎儿，是微不足道的。30pm标记妊娠带蛋白。凝乳胰蛋白酶在4℃时特异性结合大鼠肝细胞和脂肪细胞，并与人成纤维细胞和单核细胞源性巨噬细胞结合。未标记α的饱和浓度几乎完全消除了结合。2-macroglobulin .cntdot。胰蛋白酶。15pm标记的巨球蛋白复合物的结合被妊娠带蛋白的饱和浓度完全消除。胰凝乳蛋白酶。在大鼠肝细胞中，妊娠带蛋白复合物的结合率低于α。低配体浓度的2-巨球蛋白复合物。孕带蛋白复合物约为300 pM时，受体占用率达到半最大值。未标记的.alpha。2-巨球蛋白或妊娠区蛋白复合物不能加速标记妊娠区蛋白复合物的解离。2-巨球蛋白明显升高。结论妊娠带蛋白和。α。2-巨球蛋白复合物与相同的受体结合。数量上的差异可能与。alpha。2-巨球蛋白是一个四聚体，而妊娠带蛋白的功能单位可能是一个二聚体。
125I-labelled human pregnancy zone protein complexed with chymotrypsin was removed from the circulation with a half-time of 2.3 min after intravenous injection in rats. AFter 6 min about 67% of the label was present in the liver and about 3% was in the spleen, both in male and in female pregnant rats. The half-time of removal was more than 30 min for native pregnancy zone protein. Uptake into other organs, including placentae and feti, was negligible. 30 pM labelled pregnancy zone protein .cntdot. chymotrypsin was specifically bound to rat hepatocytes and adipocytes and to human fibroblasts and monocyte-derived macrophages at 4.degree.C. Binding was almost completely abolished by a saturating concentration of unlabelled .alpha.2-macroglobulin .cntdot. trypsin. Binding of 15 pM labelled macroglobulin complex was completely abolished by a saturating concentration of pregnancy zone protein .cntdot. chymotrypsin. In rat hepatocytes, binding of pregnancy zone protein complex was lower than that of .alpha.2-macroglobulin complex at low ligand concentrations. Half-maximal receptor occupancy was obtained with about 300 pM pregnancy zone protein complex. Unlabelled .alpha.2-macroglobulin or pregnancy zone protein complex failed to accelerate dissociation of the labelled pregnancy zone protein complex under conditions where dissociation of .alpha.2-macroglobulin was markedly enhanced. It is concluded that pregnancy zone protein and .alpha.2-macroglobulin complexes bind to the same receptors. The quantitative differences may be related to the fact that .alpha.2-macroglobulin is a tetramer whereas the functional unit of pregnancy zone protein is probably a dimer.