Beck B L, Henjum D C, Antonijczuk K, Zaharia O, Korza G, Ozols J, Hopfer S M, Barber A M, Sunderman F W
Department of Laboratory Medicine, University of Connecticut School of Medicine, Farmington 06030.
Res Commun Chem Pathol Pharmacol. 1992 Jul;77(1):3-16.
A Ni(2+)-binding protein (pNiXa, 45 kD, pI 8.5) discovered in Xenopus embryos, was isolated from oocytes. Based on amino acid sequences, pNiXa belongs to the serpin superfamily and shows identity to the cDNA sequence of Ep45, an estrogen-regulated hepatic serpin that contains an (HX)n-motif found in eukaryotic transcription factors. Nondenatured pNiXa, purified by Ni-affinity chromatography, inhibited bovine alpha-chymotrypsin. The presence of pNiXa in embryos when they are susceptible to Ni2+, the high avidity of pNiXa for Ni2+, and the (HX)n-motif point to pNiXa as a molecular target of Ni(2+)-teratogenesis.
在非洲爪蟾胚胎中发现的一种镍结合蛋白（pNiXa，45kD，pI 8.5），是从卵母细胞中分离出来的。根据氨基酸序列，pNiXa属于丝氨酸蛋白酶抑制剂超家族，与Ep45的cDNA序列具有同一性，Ep45是一种雌激素调节的肝脏丝氨酸蛋白酶抑制剂，含有在真核转录因子中发现的（HX）n基序。通过镍亲和层析纯化的非变性pNiXa抑制牛α-胰凝乳蛋白酶。胚胎在对镍离子敏感时pNiXa的存在、pNiXa对镍离子的高亲和力以及（HX）n基序表明pNiXa是镍离子致畸作用的分子靶点。
