Prediction of structural domains of TAP reveals details of its interaction with p15 and nucleoporins.
Vertebrate TAP is a nuclear mRNA export factor homologous to yeast Mex67p. The middle domain of TAP binds directly to p15, a protein related to the nuclear transport factor 2 (NTF2), whereas its C-terminal domain interacts with various nucleoporins, the components of the nuclear pore complex (NPC). Here, we report that the middle domain of TAP is also similar to NTF2, as well as to regions in Ras-GAP SH3 domain binding protein (G3BP) and some plant protein kinases. Based on the known three-dimensional structure of NTF2 homodimer, a heterodimerization model of TAP and p15 could be inferred. This model was confirmed by site-directed mutagenesis of residues located at the dimer interface. Furthermore, the C-terminus of TAP was found to contain a ubiquitin-associated (UBA) domain. By site-directed mutagenesis we show that a conserved loop in this domain plays an essential role in mediating TAP-nucleoporin interaction.
Suyama
M
M
EMBL, Heidelberg, Germany.
Doerks
T
T
Braun
I C
IC
Sattler
M
M
Izaurralde
E
E
Bork
P
P
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D002352:Carrier Proteins; D008565:Membrane Proteins; C122111:NXF1 protein, human; C498546:NXT1 protein, human; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins