%0 Journal Article
%T The Expression, Purification, and Characterization of a Ras Oncogene (Bras2) in Silkworm (Bombyx mori)
%A Zhengbing Lv
%A Tao Wang
%A Wenhua Zhuang
%A Dan Wang
%A Jian Chen
%A Zuoming Nie
%A Lili Liu
%A Wenping Zhang
%A Lisha Wang
%A Deming Wang
%A Xiangfu Wu
%A Jun Li
%A Lian Qian
%A Yaozhou Zhang
%J International Journal of Genomics
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/269609
%X The Ras oncogene of silkworm pupae (Bras2) may belong to the Ras superfamily. It shares 77% of its amino acid identity with teratocarcinoma oncogene 21 (TC21) related ras viral oncogene homolog-2 (R-Ras2) and possesses an identical core effector region. The mRNA of Bombyx mori Bras2 has 1412£¿bp. The open reading frame contains 603£¿bp, which encodes 200 amino acid residues. This recombinant BmBras2 protein was subsequently used as an antigen to raise a rabbit polyclonal antibody. Western blotting and real-time PCR analyses showed that BmBras2 was expressed during four developmental stages. The BmBras2 expression level was the highest in the pupae and was low in other life cycle stages. BmBras2 was expressed in all eight tested tissues, and it was highly expressed in the head, intestine, and epidermis. Subcellular localization studies indicated that BmBras2 was predominantly localized in the nuclei of Bm5 cells, although cytoplasmic staining was also observed to a lesser extent. A cell proliferation assay showed that rBmBras2 could stimulate the proliferation of hepatoma cells. The higher BmBras2 expression levels in the pupal stage, tissue expression patterns, and a cell proliferation assay indicated that BmBras2 promotes cell division and proliferation, most likely by influencing cell signal transduction. 1. Introduction Ras family small GTPases play essential roles in a variety of cellular responses including cell proliferation, differentiation, survival, transformation, and tumor development [1¨C4]. The family has approximately 20 members in mammals [5, 6], and as many as 36 Ras family genes have been identified in humans [7] with evolutionarily conserved orthologs in Drosophila, C. elegans, S. cerevisiae, S. pombe, Dictyostelium, and plants [8]. This family includes the classical Ras proteins (H-Ras, N-Ras, K4A-Ras, and K4B-Ras), the R-Ras proteins (R-Ras, TC21/R-Ras2, and M-Ras/R-Ras3), the Rap proteins (Rap1A, Rap1B, Rap2A, and Rap2B), and the Ral proteins (RalA and RalB) [9]. The first identified classical Ras (hereafter simply referred to as Ras) proteins have been studied most intensively. It was shown that Ras transduces signals from receptor-type tyrosine kinases to downstream effectors and thereby controls the proliferation and differentiation of various cell types [10]. Ras proteins function as molecular switches and are controlled by a regulated GDP/GTP cycle. Guanine nucleotide exchange factors (GEFs, e.g., SOS and mCDC25/GRF) promote the formation of active, GTP-bound Ras, whereas GTPase-activating proteins (GAPs, p120 and NF1 GAP) promote
%U http://www.hindawi.com/journals/ijg/2013/269609/