Ribosomal protein S3 interacts with the NF-κB inhibitor IκBα.
Ribosomal protein S3 (RPS3) is part of nuclear, transcriptionally active and cytoplasmic inhibitory complexes containing NF-κB variant p65. We show that in resting HEK293 cells, RPS3 interacts with NF-κB inhibitor IκBα. In contrast, efficient co-precipitation of p65 with RPS3 was only achieved in the presence of ectopic IκBα. In addition, a strong in vitro interaction was observed between RPS3 and IκBα, while binding between RPS3 and p65 was very weak. Furthermore, IκBα facilitated the reconstitution of p65 and RPS3 into one complex in vitro. Our results suggest that IκBα sequesters not only p65 but also RPS3 in the cytoplasm. This would ensure maintenance of an RPS3 pool for the NF-κB pathway as well as equimolar release of RPS3 and p65 upon stimulation.
Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria.
Tamsyn
T
Stanborough
Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria.
Johannes
J
Niederhauser
Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria.
Barbara
B
Koch
Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria.
Helmut
H
Bergler
Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria. Electronic address: brigitte.pertschy@uni-graz.at.
Brigitte
B
Pertschy
D000595:Amino Acid Sequence; D017089:Ankyrin Repeat; D057809:HEK293 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D000072000:NF-KappaB Inhibitor alpha; D011485:Protein Binding; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000737:chemistry / Q000378:metabolism*
D020672:I-kappa B Proteins; C000606204:NFKBIA protein, human; C498143:RELA protein, human; C578290:RPS3 protein, human; D012269:Ribosomal Proteins; D051996:Transcription Factor RelA; D000072000:NF-KappaB Inhibitor alpha
IκBα; NF-κB inhibitor; Nuclear factor kappa B; Ribosomal protein S3; p65