Takafuta T, Wu G, Murphy G F, Shapiro S S
Cardeza Foundation for Hematologic Research, Department of Medicine, Jefferson Medical College, Philadelphia, Pennsylvania 19107, USA.
J Biol Chem. 1998 Jul 10;273(28):17531-8. doi: 10.1074/jbc.273.28.17531.
We have cloned and sequenced a 9.4-kilobase cDNA specifying a new 280-kDa protein interacting with the cytoplasmic tail of glycoprotein (Gp) Ibalpha and showing considerable homology to actin-binding protein 280 (ABP-280) and chicken retinal filamin. We term this protein human beta-filamin. The gene for beta-filamin localizes to chromosome 3p14.3-p21.1. beta-Filamin mRNA expression was observed in many tissues and in cultured human umbilical vein endothelial cells (HUVECs); only minimal expression was detected in platelets and the megakaryocytic cell line CHRF-288. Like ABP-280, beta-filamin contains an NH2-terminal actin-binding domain, a backbone of 24 tandem repeats, and two "hinge" regions. A polyclonal antibody to the unique beta-filamin first hinge sequence identifies a strong 280-kDa band in HUVECs but only a weak band in platelets, and stains normal human endothelial cells in culture and in situ. We have confirmed the interaction of beta-filamin and GpIbalpha in platelet and HUVEC lysates. In addition, using two-hybrid analysis with deletion mutants, we have localized the binding domain for GpIbalpha in beta-filamin to residues 1862-2148, an area homologous to the GpIbalpha binding domain in ABP-280. beta-Filamin is a new member of the filamin family that may have significance for GpIbalpha function in endothelial cells and platelets.
我们克隆并测序了一段9.4千碱基的cDNA，它编码一种新的280千道尔顿蛋白质，该蛋白质与糖蛋白（Gp）Iα的细胞质尾部相互作用，并且与肌动蛋白结合蛋白280（ABP - 280）和鸡视网膜细丝蛋白具有显著同源性。我们将此蛋白质命名为人类β - 细丝蛋白。β - 细丝蛋白的基因定位于染色体3p14.3 - p21.1。在许多组织以及培养的人脐静脉内皮细胞（HUVECs）中观察到了β - 细丝蛋白mRNA的表达；在血小板和巨核细胞系CHRF - 288中仅检测到极少的表达。与ABP - 280一样，β - 细丝蛋白包含一个NH2末端肌动蛋白结合结构域、一个由24个串联重复序列组成的主干以及两个“铰链”区域。针对独特的β - 细丝蛋白第一个铰链序列的多克隆抗体在HUVECs中识别出一条强的280千道尔顿条带，但在血小板中仅识别出一条弱条带，并且能对培养的和原位的正常人内皮细胞进行染色。我们已经证实了β - 细丝蛋白与血小板和HUVEC裂解物中的GpIα相互作用。此外，通过对缺失突变体进行双杂交分析，我们已将β - 细丝蛋白中GpIα的结合结构域定位到1862 - 2148位氨基酸残基，该区域与ABP - 280中GpIα结合结构域同源。β - 细丝蛋白是细丝蛋白家族的一个新成员，可能对内皮细胞和血小板中GpIα的功能具有重要意义。
