Barry C P, Xie J, Lemmon V, Young A P
Biotechnology Center, Ohio State University, Columbus 43210.
J Biol Chem. 1993 Dec 5;268(34):25577-86.
We report the cloning and sequencing of cDNA encoding a chicken filamin protein. The 2,567 amino acid protein contains an NH2-terminal 267 amino acid actin-binding domain followed by a series of 24 repeating units that are each approximately 95 amino acids in length. The overall primary structure of filamin closely resembles that of human actin-binding protein (ABP). However, filamin lacks a 24-amino-acid insertion prior to repeat 16 that is contained within ABP. This region of human ABP is a site of calpain cleavage and is thought to confer flexibility on the molecule. Hence, it is possible that the properties of actin gels formed with either human ABP or filamin reflect the presence or absence of this insertion. Filamin is encoded within a multi-promoter transcription unit. A downstream filamin promoter (Fil1) resembles those of certain housekeeping genes and has a putative binding site for the transcription factor E2F. Thus, transcription from this promoter may be linked to the cell cycle. A second filamin promoter (Fil2) is located at least 8 kilobases upstream from the Fil1 promoter. This structural arrangement suggests that regulation of filamin gene expression is likely to be complex.
我们报道了编码鸡细丝蛋白的cDNA的克隆及测序。这种含有2567个氨基酸的蛋白质，其氨基端有一个含267个氨基酸的肌动蛋白结合结构域，随后是一系列24个重复单元，每个重复单元长度约为95个氨基酸。细丝蛋白的整体一级结构与人类肌动蛋白结合蛋白（ABP）极为相似。然而，细丝蛋白在重复单元16之前缺少ABP所包含的一个24个氨基酸的插入序列。人类ABP的这一区域是钙蛋白酶切割位点，被认为赋予了分子柔韧性。因此，由人类ABP或细丝蛋白形成的肌动蛋白凝胶的特性可能反映了该插入序列的有无。细丝蛋白由一个多启动子转录单元编码。一个下游细丝蛋白启动子（Fil1）类似于某些管家基因的启动子，并有一个转录因子E2F的假定结合位点。因此，该启动子的转录可能与细胞周期相关。第二个细丝蛋白启动子（Fil2）位于Fil1启动子上游至少8千碱基处。这种结构安排表明细丝蛋白基因表达的调控可能很复杂。
