背景
function:A phosphoprotein adapter involved in the XPO1-mediated U snRNA export from the nucleus. Bridge components required for U snRNA export, the cap binding complex (CBC)-bound snRNA on the one hand and the GTPase Ran in its active GTP-bound form together with the export receptor XPO1 on the other. Its phosphorylation in the nucleus is required for U snRNA export complex assembly and export, while its dephosphorylation in the cytoplasm causes export complex disassembly. It is recycled back to the nucleus via the importin alpha/beta heterodimeric import receptor. The directionality of nuclear export is thought to be conferred by an asymmetric distribution of the GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus. Its compartmentalized phosphorylation cycle may also contribute to the directionality of export. Binds strongly to m7G-capped U1 and U5 small nuclear RNAs (snRNAs) in a sequence-unspecific manner and phosphorylation-independent manner (By similarity). Plays also a role in the biogenesis of U3 small nucleolar RNA (snoRNA). Involved in the U3 snoRNA transport from nucleoplasm to Cajal bodies. Binds strongly to m7G-capped U3, U8 and U13 precursor snoRNAs and weakly to trimethylated (TMG)-capped U3, U8 and U13 snoRNAs. Binds also to telomerase RNA.,PTM:Phosphorylated in the nucleus. Dephosphorylated in the cytoplasm (By similarity). Phosphorylated upon DNA damage, probably by ATM or ATR.,PTM:Phosphorylated upon DNA damage, probably by ATM or ATR.,similarity:Belongs to the PHAX family.,subcellular location:Located in the nucleoplasm and Cajal bodies. Shuttles between the nucleus and the cytoplasm. Shuttles between the nucleoplasm and Cajal bodies.,subunit:Found in a U snRNA export complex with PHAX/RNUXA, NCBP1, NCBP2, RAN, XPO1 and m7G-capped RNA. Part of a precomplex with PHAX/RNUXA, NCBP1, NCBP2 and m7G-capped RNA. Interacts with NCBP1 (By similarity). Found in a complex with snoRNA.,
