Le Gall Sylvain M, Meneton Pierre, Mauduit Philippe, Dreux Catherine
Institut de Biochimie et Biophysique Moléculaire et Cellulaire CNRS UMR 8619, Université Paris XI Bât 430, 91405 Orsay Cedex, France.
Regul Pept. 2004 Oct 15;122(2):119-29. doi: 10.1016/j.regpep.2004.06.008.
Epidermal growth factor (EGF) is present in kidney membranes as an integral type I precursor protein, enzymatically processed to release immunoreactive materials in urine or incubation medium. The aim of this work was the elucidation of both the anchor of the serine protease activity that processes pro-EGF, and the determination of the steps of the enzymatic processing. Quantification of EGF containing molecules by RIA following gel filtration analysis demonstrated that the membrane precursor is first shed from the kidney membrane principally into a 170-kDa soluble precursor. This entire ectodomain is further processed into a 70-kDa precursor and finally into the mature 5.9 kDa urinary EGF. These species correspond to the ones found in urines. Both shedding and maturation events are clearly realized by membrane anchored serine protease activity, which remains active in detergent. By use of wild-type and knockout mice urines, we found that tissue kallikrein (TK) was not involved in the regulation of this processing.
表皮生长因子（EGF）作为一种完整的I型前体蛋白存在于肾膜中，经酶处理后可在尿液或孵育培养基中释放出免疫反应性物质。这项工作的目的是阐明处理前体EGF的丝氨酸蛋白酶活性的锚定物，以及确定酶促加工的步骤。凝胶过滤分析后通过放射免疫分析（RIA）对含EGF分子进行定量表明，膜前体首先从肾膜上脱落，主要进入一种170 kDa的可溶性前体。这个完整的胞外结构域进一步加工成一种70 kDa的前体，最终加工成成熟的5.9 kDa尿EGF。这些形式与尿液中发现的形式相对应。脱落和成熟事件均由膜锚定丝氨酸蛋白酶活性明确实现，该活性在去污剂中仍保持活性。通过使用野生型和基因敲除小鼠的尿液，我们发现组织激肽释放酶（TK）不参与这种加工的调节。
