Kaplan R, Jaye M, Burgess W H, Schlaepfer D D, Haigler H T
Division of Molecular Biology, Rorer Biotechhology Inc., Springfield, Virginia 22151.
J Biol Chem. 1988 Jun 15;263(17):8037-43.
Endonexin II is a member of the family of Ca2+-dependent phospholipid binding proteins known as annexins. We cloned human endonexin II cDNA and expressed it in Escherichia coli. The apparent size and Ca2+-dependent phospholipid binding properties of purified recombinant endonexin II were indistinguishable from those of the placental protein. A single mRNA of approximately 1.6 kilobase pairs was found to be expressed in human cell lines and placenta and was in close agreement with the length of the cDNA clone (1.59 kilobase pairs). The cDNA predicted a 320-amino acid protein with a sequence that was in agreement with the previously determined partial amino acid sequence of endonexin II isolated from placenta. Endonexin II contained 58, 46, and 43% sequence identity to protein II, calpactin I (p36, protein I), and lipocortin I (p35), respectively. The partial sequence of bovine endonexin I was aligned with the sequence of endonexin II to give 63% sequence identity. Like these other proteins, endonexin II had a 4-fold internal repeat of approximately 70 residues preceded by an amino-terminal domain lacking similarity to the repeated region. It also had significant sequence identity with 67-kDa calelectrin (p68), a protein with an 8-fold internal repeat. Comparing the amino-terminal domains of these four proteins of known sequence revealed that, in general, only endonexin II and protein II had significant sequence identity (29%). Endonexin II was not phosphorylated by Ca2+/phospholipid-dependent enzyme (protein kinase C) even though it contained a threonine at a position analogous to the protein kinase C phosphorylation sites of lipocortin I, calpactin I, and protein II.
内毒素 II 是 annexins 家族中依赖 Ca2+ 的磷脂结合蛋白成员。我们克隆了人内毒素 II cDNA 并在大肠杆菌中表达。纯化的重组内毒素 II 的表观大小和 Ca2+ 依赖性磷脂结合特性与胎盘蛋白的特性无法区分。在人细胞系和胎盘中发现了一种约 1.6 千碱基对的单一 mRNA，这与 cDNA 克隆的长度（1.59 千碱基对）非常一致。该 cDNA 预测了一种 320 个氨基酸的蛋白质，其序列与先前从胎盘中分离出的内毒素 II 的部分氨基酸序列一致。内毒素 II 与蛋白 II、钙结合蛋白 I（p36，蛋白 I）和脂皮质蛋白 I（p35）的序列同一性分别为 58%、46% 和 43%。牛内毒素 I 的部分序列与内毒素 II 的序列比对后，序列同一性为 63%。与这些其他蛋白质一样，内毒素 II 有一个约 70 个残基的 4 倍内部重复序列，其前面是一个与重复区域缺乏相似性的氨基末端结构域。它与 67 kDa 的钙电蛋白（p68）也有显著的序列同一性，后者是一种具有 8 倍内部重复序列的蛋白质。比较这四种已知序列的蛋白质的氨基末端结构域发现，一般来说，只有内毒素 II 和蛋白 II 有显著的序列同一性（29%）。尽管内毒素 II 在类似于脂皮质蛋白 I、钙结合蛋白 I 和蛋白 II 的蛋白激酶 C 磷酸化位点的位置含有一个苏氨酸，但它不会被 Ca2+/磷脂依赖性酶（蛋白激酶 C）磷酸化。
