Venables J P, Elliott D J, Makarova O V, Makarov E M, Cooke H J, Eperon I C
Department of Biochemistry, University of Leicester, University Road, Leicester LE1 7RH, UK.
Hum Mol Genet. 2000 Mar 22;9(5):685-94. doi: 10.1093/hmg/9.5.685.
The RBMY gene family is found on the Y chromosome of all mammals, and microdeletions are strongly associated with infertility in men. RBMY expresses RBM only in the nuclei of germ cells, whereas its X chromosome homologue, RBMX, expresses hnRNP G ubiquitously. We show here that RBM, hnRNP G and a novel testis-specific relative, termed hnRNP G-T, interact with Tra2beta, an activator of pre-mRNA splicing that is ubiquitous but highly expressed in testis. Endogenous hnRNP G and Tra2beta proteins are associated in HeLa nuclear extracts. RBM and Tra2beta co-localize in two major domains in human spermatocyte nuclei. Phosphorylation enhanced the interaction and reduced competing RNA binding to the interaction domains. Incubation with the protein interaction domain of RBM inhibited splicing in vitro of a specific pre-mRNA substrate containing an essential enhancer bound by Tra2beta. The RNA-binding domain of RBM affected 5' splice site selection. We conclude that the hnRNP G family of proteins is involved in pre-mRNA splicing and infer that RBM may be involved in Tra2beta-dependent splicing in spermatocytes.
RBMY基因家族存在于所有哺乳动物的Y染色体上，微缺失与男性不育密切相关。RBMY仅在生殖细胞的细胞核中表达RBM，而其X染色体同源物RBMX则在全身广泛表达hnRNP G。我们在此表明，RBM、hnRNP G以及一种新的睾丸特异性相关蛋白hnRNP G-T，与Tra2β相互作用，Tra2β是一种前体mRNA剪接激活因子，在全身广泛存在，但在睾丸中高表达。内源性hnRNP G和Tra2β蛋白在HeLa细胞核提取物中相互关联。RBM和Tra2β在人类精母细胞核中的两个主要区域共定位。磷酸化增强了相互作用，并减少了与相互作用结构域的竞争性RNA结合。与RBM的蛋白质相互作用结构域孵育可抑制体外对含有Tra2β结合的必需增强子的特定前体mRNA底物的剪接。RBM的RNA结合结构域影响5'剪接位点的选择。我们得出结论，hnRNP G蛋白家族参与前体mRNA剪接，并推断RBM可能参与精母细胞中Tra2β依赖性剪接。
