RNA U small nuclear RNA export adapter protein (phosphorylated adapter RNA export protein, RNUXA, PHAX)

Function

• phosphoprotein adapter involved in the XPO1-mediated U snRNA export from the nucleus
  • components of the nuclear export include:
    • cap binding complex snRNA GTP-bound GTPase Ran export receptor XPO1
• phosphorylation in the nucleus is required for U snRNA export complex assembly
• dephosphorylation in the cytoplasm causes export complex disassembly
• recycled back to the nucleus via the importin alpha/beta heterodimeric import receptor
• directionality of nuclear export conferred by an asymmetric distribution of GTP- & GDP-bound forms of Ran between the cytoplasm & nucleu
• compartmentalized phosphorylation cycle may also contribute to the directionality of export
• binds strongly to m7G-capped U1 & U5 small nuclear RNAs (sequence-nonspecific & phosphorylation- independent
• biogenesis of U3 small nucleolar RNA (snoRNA)
• U3 snoRNA transport from nucleoplasm to Cajal bodies
• binds strongly to m7G-capped U3, U8 & U13 precursor snoRNAs & weakly to trimethylated [TMG]-capped U3, U8 & U13 snoRNAs
• binds to telomerase RNA
• component of U snRNA export complex
• interacts with NCBP1 14 forms complex with snoRNA

Compartment

• nucleus, cytoplasm, nucleoplasm, Cajal bodies
• shuttles between the nucleus & the cytoplasm
• shuttles between the nucleoplasm & Cajal bodies

More general terms

• phosphoprotein
• RNA-binding protein

Component of

• U snRNA export complex

Database

• OMIM: https://mirror.omim.org/entry/604924
• UniProt: http://www.uniprot.org/uniprot/Q9H814.html