Fitzgerald Carolyn, Sikora Curtis, Lawson Vannice, Dong Karen, Cheng Min, Oko Richard, van der Hoorn Frans A
Department of Biochemistry and Molecular Biology, University of Calgary, 330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
J Biol Chem. 2006 Dec 15;281(50):38172-80. doi: 10.1074/jbc.M606010200. Epub 2006 Oct 12.
Post-transcriptional mechanisms including differential splicing expand the protein repertoire beyond that provided by the one gene-one protein model. Trans-splicing has been observed in mammalian systems but is low level (sometimes referred to as noise), and a contribution to hybrid protein expression is unclear. In the study of rat sperm tail proteins a cDNA, called 1038, was isolated representing a hybrid mRNA derived in part from the ornithine decarboxylase antizyme 3 (Oaz3) gene located on rat chromosome 2 fused to sequences encoded by a novel gene on chromosome 4. Cytoplasmic Oaz3 mRNA is completely testis specific. However, in several tissues Oaz3 is transcribed and contributes to hybrid 1038 mRNA synthesis, without concurrent Oaz3 mRNA synthesis. 1038 mRNA directs synthesis of a hybrid 14-kDa protein, part chromosome 2- and part chromosome 4-derived as shown in vitro and in transfected cells. Antisera that recognize a chromosome 4-encoded C-terminal peptide confirm the hybrid character of endogenous 14-kDa protein and its presence in sperm tail structures and 1038-positive tissue. Our data suggest that the testis-specific OAZ3 gene may be an example of a mammalian gene that in several tissues is transcribed to contribute to a hybrid mRNA and protein. This finding expands the repertoire of known mechanisms available to cells to generate proteome diversity.
包括可变剪接在内的转录后机制使蛋白质种类超出了一个基因一种蛋白质模型所提供的范围。反式剪接在哺乳动物系统中已被观察到，但水平较低（有时被称为噪音），其对杂合蛋白表达的贡献尚不清楚。在对大鼠精子尾部蛋白质的研究中，分离出了一个名为1038的cDNA，它代表一种杂合mRNA，部分来源于大鼠2号染色体上的鸟氨酸脱羧酶抗酶3（Oaz3）基因，与4号染色体上一个新基因编码的序列融合。细胞质中的Oaz3 mRNA完全是睾丸特异性的。然而，在几个组织中，Oaz3被转录并参与杂合1038 mRNA的合成，同时没有Oaz3 mRNA的合成。1038 mRNA指导合成一种14 kDa的杂合蛋白，如在体外和转染细胞中所示，部分来源于2号染色体，部分来源于4号染色体。识别4号染色体编码的C末端肽的抗血清证实了内源性14 kDa蛋白的杂合特性及其在精子尾部结构和1038阳性组织中的存在。我们的数据表明，睾丸特异性的OAZ3基因可能是哺乳动物基因的一个例子，该基因在几个组织中被转录以产生杂合mRNA和蛋白质。这一发现扩展了细胞可利用的已知机制，以产生蛋白质组多样性。
