Hanson Laura K, Dalton Bridget L, Cageao Laura F, Brock Rachel E, Slater Jacquelyn S, Kerry Julie A, Campbell Ann E
Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA 23501, USA.
Virology. 2005 Apr 10;334(2):166-77. doi: 10.1016/j.virol.2005.01.046.
US22 gene family members m142 and m143 are essential for replication of murine cytomegalovirus (MCMV). Their transcripts are produced with immediate-early kinetics, but little else is known about these viral genes. Unlike their transcripts, the m142 and m143 gene products (pm142, pm143) were not expressed until early times post-infection, with levels increasing over the course of infection. Both pm142 and pm143 were predominantly cytoplasmic, but cellular fractionation studies confirmed that the proteins were present in the nucleus as well. In addition, pm142 was detected within the virion. Both the m142 and m143 promoters were strongly upregulated by viral infection or by MCMV IE1. However, UV-inactivated virus and IE3 upregulated only the m142 promoter. When tested for transcriptional transactivating activity, neither m142 nor m143 demonstrated significant activity, either alone or in combination with the major immediate-early gene products. This failure to transactivate, along with their essential nature, makes m142 and m143 unique among the immediate-early genes of the US22 gene family.
US22基因家族成员m142和m143对鼠巨细胞病毒（MCMV）的复制至关重要。它们的转录本以立即早期动力学产生，但关于这些病毒基因的其他信息知之甚少。与它们的转录本不同，m142和m143基因产物（pm142、pm143）直到感染后早期才表达，其水平在感染过程中逐渐升高。pm142和pm143主要位于细胞质中，但细胞分级分离研究证实这些蛋白质也存在于细胞核中。此外，在病毒粒子中检测到了pm142。m142和m143启动子均被病毒感染或MCMV IE1强烈上调。然而，紫外线灭活病毒和IE3仅上调m142启动子。在测试转录反式激活活性时，m142和m143单独或与主要立即早期基因产物联合使用时均未表现出显著活性。这种无法反式激活以及它们的必需性质，使得m142和m143在美国22基因家族的立即早期基因中独一无二。
