PHAX Proteins

Protein Information

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. 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.

Synonyms

26 kDa resiniferatoxin-binding protein; 2810055C14Rik; 4933427L19Rik; AU018701; AU018854; cytosolic resiniferatoxin-binding protein; D18Ertd65e; p55; PHAX; Phosphorylated adapter RNA export protein; phosphorylated adaptor for RNA export; phosphorylation regulated; RBP-2; RBP-26; resiniferatoxin-binding protein 2; RNA U small nuclear RNA export adapter protein; RNA U, small nuclear RNA export adapter (phosphorylation regulated); RNA U, small nuclear RNA export adaptor; RNA U, small nuclear RNA export adaptor (phosphorylation regulated); Rnuxa; RTX-42