Thevananther S, Kolli A H, Devarajan P
Department of Pediatrics, Division of Pediatric Nephrology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
J Biol Chem. 1998 Sep 11;273(37):23952-8. doi: 10.1074/jbc.273.37.23952.
Ankyrins are a family of adapter molecules that mediate linkages between integral membrane and cytoskeletal proteins. Such interactions are crucial to the polarized distribution of membrane proteins in transporting epithelia. We have cloned and characterized a novel 190-kDa member of this family from a rat kidney cDNA library, which we term AnkG190 based on the predicted size and homology with the larger neuronal AnkG isoform. AnkG190 displays a unique 31-residue amino terminus, a repeats domain consisting of 24 repetitive 33-residue motifs, a spectrin binding domain, and a truncated regulatory domain. Probes derived from the unique amino terminus hybridize to an 8-kilobase message exclusively in kidney and lung and specifically to the kidney outer medullary collecting ducts by in situ hybridization. Transfections of Madin-Darby canine kidney and COS-7 epithelial cell lines with a full-length AnkG190 construct result in (a) expression at the lateral plasma membrane, (b) functional assembly with the cytoskeleton, and (c) interaction with at least one membrane protein, the Na,K-ATPase. Two independent Na,K-ATPase binding domains on AnkG190 are demonstrated as follows: one within the distal 12 ankyrin repeats, and a second site within the spectrin binding domain. Thus, ankyrins may interact with integral membrane proteins in a pleiotropic manner that may involve complex tertiary structural determinants.
锚蛋白是一类衔接分子，介导整合膜蛋白与细胞骨架蛋白之间的连接。这种相互作用对于转运上皮细胞中膜蛋白的极性分布至关重要。我们从大鼠肾脏cDNA文库中克隆并鉴定了该家族一个新的190-kDa成员，根据预测大小以及与较大的神经元AnkG异构体的同源性，我们将其命名为AnkG190。AnkG190具有独特的31个氨基酸残基的氨基末端、一个由24个重复的33个氨基酸残基基序组成的重复结构域、一个血影蛋白结合结构域和一个截短的调节结构域。源自独特氨基末端的探针通过原位杂交，仅在肾脏和肺中与一个8千碱基的信使RNA杂交，并且特异性地与肾脏外髓集合管杂交。用全长AnkG190构建体转染Madin-Darby犬肾和COS-7上皮细胞系，结果显示：(a) 在外侧质膜表达，(b) 与细胞骨架进行功能性组装，以及(c) 与至少一种膜蛋白钠钾ATP酶相互作用。AnkG190上两个独立的钠钾ATP酶结合结构域如下所示：一个在远端12个锚蛋白重复序列内，另一个位点在血影蛋白结合结构域内。因此，锚蛋白可能以多效性方式与整合膜蛋白相互作用，这可能涉及复杂的三级结构决定因素。
