exportin-7; exp7; Ran-binding protein 16 (XPO7, KIAA0745, RANBP16)

Function

• mediates nuclear export of proteins (cargos) with broad substrate specificity
• in the nucleus, binds cooperatively to its cargo & to the GTPase Ran in its active GTP-bound form
• docking of the nuclear export complex (containing XPO7, Ran-GTP & the cargo) to the nuclear pore complex is mediated through binding to nucleoporins
• upon transit of a nuclear export complex into the cytoplasm, disassembling of the complex & hydrolysis of Ran-GTP to Ran-GDP (induced by RANBP1 & RANGAP1, respectively) cause release of the cargo from the export receptor (nuclear export complex)
• XPO7 then returns to the nuclear compartment to mediate another round of transport
• directionality of nuclear export is thought to be conferred by an asymmetric distribution of the GTP- & GDP-bound forms of Ran between the cytoplasm & nucleus
• binds to nucleoporins
• found in a complex with XPO7, EIF4A1, ARHGAP1, VPS26A, VPS29, VPS35 & SFN
• interacts with ARHGAP1 & SFN
• interacts with Ran & cargo proteins (GTP-dependent)

Structure

• belongs to the exportin family
  • contains 1 importin N-terminal domain

Compartment

• cytoplasm
• nucleus, nuclear pore complex
• shuttles between the nucleus & the cytoplasm (probable)

Expression

• high expression in testis, thyroid & bone marrow
• low expression in lung, liver & small intestine
• no expression in thymus
• other tissues with intermediate expression
• expressed in erythrocytes

Pathology

• overexpressed in erythrocytes of patients with hereditary non-spherocytic hemolytic anemia of unknown etiology

More general terms

• exportin
• phosphoprotein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=23039
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:23039
• OMIM: https://mirror.omim.org/entry/606140
• UniProt: http://www.uniprot.org/uniprot/Q9UIA9.html