The kappa promoter penta-decamer binding protein CBF-A interacts specifically with nucleophosmin in the nucleus only.
CArG box-binding factor-A (CBF-A) interacts with the penta-decamer (pd) element that is a conserved sequence element within mouse Vkappa promoters. The pd element acts in synergy with the octamer element to stimulate kappa transcription, especially in later stages of B cell development. To get further insight in the mechanism for CBF-A action we have characterised its protein-protein interactions. We show here that CBF-A interacts specifically with nucleophosmin (NPM). This interaction occurs via the homo-oligomerisation domain of NPM and the N-terminus of CBF-A and was exclusive for the nuclear compartment while the two proteins failed to interact in the cytosol. In contrast, CBF-A formed homocomplexes in this compartment. CBF-A was also shown to localise to the nucleoli, most likely dependent on a functional interaction with NPM. Lastly, the sequence fine specificity of CBF-A complexes in the nucleus and cytoplasm were found to differ and nuclear protein-DNA complexes were shown to contain NPM. Thus, CBF-A participates in several protein-protein interactions that may modulate its subcellular localisation and target gene specificity.
Aranburu
Alaitz
A
Inflammation and Immunology Unit, BMC I:13, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden.
Bennett
Matthew
M
Leanderson
Tomas
T
D000818:Animals; D001665:Binding Sites; D023081:CCAAT-Binding Factor / Q000378:metabolism*; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D018390:Gene Targeting; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D009687:Nuclear Proteins / Q000378:metabolism*; D000090243:Nucleophosmin; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014162:Transfection
D023081:CCAAT-Binding Factor; D004268:DNA-Binding Proteins; D007145:Immunoglobulin kappa-Chains; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D000090243:Nucleophosmin