Distinct receptors for insulin-like growth factor I in rat renal glomeruli and tubules.
Distinct receptors for insulin-like growth factor I in rat renal glomeruli and tubules.
复制标题
大鼠肾小球和肾小管中胰岛素样生长因子 I 的不同受体。
DOI：
10.1152/ajpendo.1988.255.4.e504
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Meezan,E
中科院分区：
文献类型：
--
作者：
Pillion,DJ;Haskell,JF;Meezan,E
通过用磁性氧化铁颗粒灌注大鼠肾脏以选择性地将含铁肾小球与肾小管分离的程序获得肾小球和肾小管的纯化制剂。清洁剂可溶性提取物的肾小球和肾小管膜表现出高亲和力，125 I标记的胰岛素样生长因子I（125 I-IGF-I）的特异性结合，而这种肽激素的降解是最小的，在22摄氏度，在2.5 mM EDTA和5 mM N-乙基马来酰亚胺的存在下孵育90分钟。这些受体对IGF-I的亲和力在两种类型的肾组织中似乎是相同的，因为在存在约3 × 10（-9）M未标记IGF-I的情况下，125 I-IGF-I与肾小球和肾小管组织结合的抑制率均为50%。相比之下，胰岛素在阻断125 I-IGF-I与任一组织结合方面的效果要差得多，需要1 × 10（-6）M胰岛素才能产生50%的结合抑制。相对于125 I-IGF-I结合，125 I-胰岛素结合到肾小球和肾小管组织的每毫克蛋白质显著较低。125 I-IGF-I特异性交联至肾小球受体亚单位，在40 mM二硫苏糖醇存在下，肾小球受体亚单位在十二烷基硫酸钠聚丙烯酰胺凝胶上迁移为相对分子量（Mr）为140，000 - 150，000的两条离散条带。相比之下，125 I-IGF-I与管状受体亚基交联，其作为两个离散条带迁移，但位置略有不同，Mr为120，000 - 140，000。（250字处删节）
Purified preparations of renal glomeruli and tubules were obtained by a procedure involving perfusion of rat kidneys with magnetic iron oxide particles to selectively separate the iron-containing glomeruli from the nonmagnetic tubules. Detergent-soluble extracts of both renal glomerular and tubular membranes showed high-affinity, specific binding of 125I-labeled insulin-like growth factor I (125I-IGF-I), whereas degradation of this peptide hormone was minimal during a 90-min incubation at 22 degrees C in the presence of 2.5 mM EDTA and 5 mM N-ethylmaleimide. The affinity of these receptors for IGF-I appeared identical in the two types of renal tissue, since 50% inhibition of 125I-IGF-I binding to both glomerular and tubular tissue occurred in the presence of approximately 3 x 10(-9) M unlabeled IGF-I. In contrast, insulin was much less effective at blocking 125I-IGF-I binding to either tissue, with 1 x 10(-6) M insulin required to produce 50% inhibition of binding. Relative to 125I-IGF-I binding, 125I-insulin binding to glomerular and tubular tissue was significantly lower per milligram protein. 125I-IGF-I was specifically cross-linked to a glomerular receptor subunit that migrated as two discrete bands with relative molecular weight (Mr) of 140,000-150,000 on sodium dodecyl sulfate polyacrylamide gels in the presence of 40 mM dithiothreitol. In contrast, 125I-IGF-I was cross-linked to a tubular receptor subunit that migrated as two discrete bands but at a slightly different position, with Mr of 120,000-140,000.(ABSTRACT TRUNCATED AT 250 WORDS)