Prendergast G C, Ziff E B
Department of Biochemistry, New York University Medical Center, NY 10016.
EMBO J. 1991 Apr;10(4):757-66. doi: 10.1002/j.1460-2075.1991.tb08007.x.
We describe the characterization of a novel cDNA, mbh1 (myc basic motif homolog-1), which was found during a search for candidate factors which might interact with the c-Myc oncoprotein. Embedded within the amino acid sequence encoded by mbh1 is a region distantly related to the basic/helix-loop-helix (B/HLH) DNA-binding motif and a potential nuclear localization signal. Mbh1 encodes a polypeptide structurally similar to the actin-severing proteins gelsolin and severin. Translation of mbh1 RNA in rabbit reticulocyte extracts produces an approximately 45 kd protein capable of binding actin-coupled agarose beads in vitro in a Ca2(+)-dependent manner. Antiserum raised to a trpE/mbh1 bacterial fusion protein recognizes an approximately 45 kb protein in murine 3T3 fibroblasts, suggesting that the cDNA encodes the complete Mbh1 protein. Examination of Mbh1 localization in 3T3 fibroblasts by indirect immunofluorescence reveals a larger cell population showing diffuse staining, and a smaller population exhibiting a distinct nuclear stain. Western analysis corroborates this intracellular localization and indicates that total cellular levels and localization of Mbh1 are not affected by the cell growth state. The data suggest that Mbh1 may play a role in regulating cytoplasmic and/or nuclear architecture through potential interactions with actin.
我们描述了一种新型cDNA，即mbh1（myc基本基序同源物-1）的特征，它是在寻找可能与c-Myc癌蛋白相互作用的候选因子过程中发现的。mbh1编码的氨基酸序列中包含一个与碱性/螺旋-环-螺旋（B/HLH）DNA结合基序有远缘关系的区域以及一个潜在的核定位信号。Mbh1编码一种在结构上与肌动蛋白切割蛋白凝溶胶蛋白和肌动蛋白切断蛋白相似的多肽。在兔网织红细胞提取物中对mbh1 RNA进行翻译会产生一种约45 kd的蛋白质，该蛋白质能够在体外以Ca2(+)依赖的方式结合肌动蛋白偶联的琼脂糖珠。针对trpE/mbh1细菌融合蛋白产生的抗血清可识别小鼠3T3成纤维细胞中一种约45 kb的蛋白质，这表明该cDNA编码完整的Mbh1蛋白。通过间接免疫荧光检查3T3成纤维细胞中Mbh1的定位发现，较大细胞群体呈现弥漫性染色，较小群体则表现出明显的核染色。蛋白质印迹分析证实了这种细胞内定位，并表明Mbh1的总细胞水平和定位不受细胞生长状态的影响。数据表明，Mbh1可能通过与肌动蛋白的潜在相互作用在调节细胞质和/或核结构中发挥作用。
