兔尿Tamm-Horsfall糖蛋白的周转率

The turnover rate of rabbit urinary Tamm-Horsfall glycoprotein.

作者信息

Grant A M, Neuberger A

出版信息

Biochem J. 1973 Nov;136(3):659-68. doi: 10.1042/bj1360659.

DOI:10.1042/bj1360659

PMID:4780692

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1166001/

Abstract

The turnover rate of urinary Tamm-Horsfall glycoprotein in rabbits was determined by two different methods. The first involved measurement of the pool size of the glycoprotein in rabbit kidney and the daily urinary excretion rate by a radioimmunoassay from which the turnover rate was calculated. 2. The second method made use of the incorporation in vivo of Na(2) (14)CO(3) and sodium [(14)C]acetate. After a single intramuscular injection of one of these compounds, urine collections were made every 24h and the glycoprotein was isolated and its specific radioactivity was determined. 3. Incorporation of the label into urinary HCO(3) (-), urea and plasma fibrinogen was also examined. The specific radio-activities of the O-acetyl, sialic acid, aspartic acid and glutamic acid residues isolated from the Tamm-Horsfall glycoprotein were compared and their half-lives were compared with that of the intact glycoprotein. The two methods gave results in quite close agreement and indicated a half-life for the glycoprotein of approx. 9h. 4. An attempt was made to localize the glycoprotein within the kidney and within the cell. It is present throughout the kidney, but was not detected in the brush-border fraction isolated from the proximal tubules. From differential cell-centrifugation studies, the glycoprotein seemed to be predominantly present in the soluble fraction (100000g supernatant). This suggests that it is either largely a soluble cytoplasmic component or is very loosely bound to a membrane, being readily released under the gentlest homogenization procedure. 5. The half-life of Tamm-Horsfall glycoprotein in human kidney was found by the radioimmunoassay method to be approx. 16h. The similarity between the composition of Tamm-Horsfall glycoprotein and human erythropoietin is discussed.

摘要

采用两种不同方法测定了家兔尿中Tamm-Horsfall糖蛋白的周转率。第一种方法是通过放射免疫测定法测量家兔肾脏中该糖蛋白的池大小和每日尿排泄率，进而计算周转率。2. 第二种方法利用体内注入Na₂¹⁴CO₃和¹⁴C标记的醋酸钠。单次肌肉注射其中一种化合物后，每24小时收集尿液，分离糖蛋白并测定其比放射性。3. 还检测了标记物掺入尿中HCO₃⁻、尿素和血浆纤维蛋白原的情况。比较了从Tamm-Horsfall糖蛋白中分离出的O-乙酰基、唾液酸、天冬氨酸和谷氨酸残基的比放射性，并将它们的半衰期与完整糖蛋白的半衰期进行了比较。两种方法得出的结果相当吻合，表明该糖蛋白的半衰期约为9小时。4. 尝试将该糖蛋白定位在肾脏内和细胞内。它存在于整个肾脏中，但在从近端小管分离出的刷状缘部分未检测到。通过差速细胞离心研究，该糖蛋白似乎主要存在于可溶性部分（100000g上清液）。这表明它要么主要是一种可溶性细胞质成分，要么与膜结合非常松散，在最温和的匀浆程序下很容易释放出来。5. 通过放射免疫测定法发现，人肾脏中Tamm-Horsfall糖蛋白的半衰期约为16小时。讨论了Tamm-Horsfall糖蛋白与人促红细胞生成素组成之间的相似性。