表皮生长因子结合蛋白激活可溶性和受体结合型单链尿激酶型纤溶酶原激活剂。

Epidermal growth factor-binding protein activates soluble and receptor-bound single chain urokinase-type plasminogen activator.

作者信息

Wolf B B, Brown M D

机构信息

Department of Internal Medicine, University of California at San Diego 92103, USA.

出版信息

FEBS Lett. 1995 Dec 4;376(3):177-80. doi: 10.1016/0014-5793(95)01234-8.

DOI:10.1016/0014-5793(95)01234-8

PMID:7498536

Abstract

Epidermal growth factor-binding protein (EGF-BP) is a serine proteinase that reversibly associates with epidermal growth factor (EGF). We analyzed the reaction of EGF-BP with urokinase type plasminogen activator (u-PA), a serine proteinase that promotes pericellular proteolysis and cellular migration. EGF-BP cleaved single chain u-PA (scu-PA) between Lys158 and Ile159, converting the zymogen into enzymatically active two-chain u-PA (tcu-PA), as shown by SDS-PAGE, N-terminal sequence analysis, and enzymatic assay. The kcat and Km of the activation reaction were (5.6 +/- 0.6) x 10(-2)s-1 and 2.0 +/- 0.3 microM, yielding a catalytic efficiency of 2.8 x 10(4) M-1.s-1. EGF-BP also activated scu-PA bound to receptors on U937 monocytes as demonstrated by the generation of amidase activity against a tcu-PA-specific fluorogenic substrate. By activating scu-PA, EGF-BP may initiate u-PA-dependent cell surface proteolysis and therefore enhance EGF activities that require cellular migration and/or tissue remodeling.

摘要

表皮生长因子结合蛋白（EGF - BP）是一种丝氨酸蛋白酶，它能与表皮生长因子（EGF）可逆性结合。我们分析了EGF - BP与尿激酶型纤溶酶原激活剂（u - PA）的反应，u - PA是一种促进细胞周围蛋白水解和细胞迁移的丝氨酸蛋白酶。如SDS - PAGE、N端序列分析和酶活性测定所示，EGF - BP在Lys158和Ile159之间切割单链u - PA（scu - PA），将酶原转化为具有酶活性的双链u - PA（tcu - PA）。激活反应的kcat和Km分别为(5.6±0.6)×10⁻² s⁻¹和2.0±0.3 μM，催化效率为2.8×10⁴ M⁻¹·s⁻¹。如针对tcu - PA特异性荧光底物产生的酰胺酶活性所示，EGF - BP还能激活U937单核细胞受体上结合的scu - PA。通过激活scu - PA，EGF - BP可能启动u - PA依赖的细胞表面蛋白水解，从而增强需要细胞迁移和/或组织重塑的EGF活性。