Fillman Christy, Lykke-Andersen Jens
Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA.
Curr Opin Cell Biol. 2005 Jun;17(3):326-31. doi: 10.1016/j.ceb.2005.04.002.
Decapping is a central step in eukaryotic mRNA turnover. Recent studies have identified several factors involved in catalysis and regulation of decapping. These include the following: an mRNA decapping complex containing the proteins Dcp1 and Dcp2; a nucleolar decapping enzyme, X29, involved in the degradation of U8 snoRNA and perhaps of other capped nuclear RNAs; and a decapping 'scavenger' enzyme, DcpS, that hydrolyzes the cap structure resulting from complete 3'-to-5' degradation of mRNAs by the exosome. Several proteins that stimulate mRNA decapping by the Dcp1:Dcp2 complex co-localize with Dcp1 and Dcp2, together with Xrn1, a 5'-to-3' exonuclease, to structures in the cytoplasm called processing bodies. Recent evidence suggests that the processing bodies may constitute specialized cellular compartments of mRNA turnover, which suggests that mRNA and protein localization may be integral to mRNA decay.
脱帽是真核生物mRNA周转的核心步骤。最近的研究已经鉴定出了几种参与脱帽催化和调控的因子。这些因子包括：一种包含Dcp1和Dcp2蛋白的mRNA脱帽复合体；一种核仁脱帽酶X29，它参与U8小核仁RNA以及可能其他带帽核RNA的降解；还有一种脱帽“清除”酶DcpS，它能水解由外切体从mRNA 3' 端到5' 端完全降解所产生的帽结构。几种通过Dcp1:Dcp2复合体刺激mRNA脱帽的蛋白质与Dcp1和Dcp2以及5' 到3' 外切核酸酶Xrn1共同定位于细胞质中称为加工小体的结构上。最近的证据表明，加工小体可能构成了mRNA周转的特殊细胞区室，这表明mRNA和蛋白质的定位可能是mRNA降解所必需的。
