Translationally controlled tumor protein interacts with the third cytoplasmic domain of Na,K-ATPase alpha subunit and inhibits the pump activity in HeLa cells.
Translationally controlled tumor protein (TCTP) is a growth-related protein under transcriptional as well as translational control. We screened a rat skeletal muscle cDNA library using yeast two-hybrid system and found that TCTP interacts with the third large cytoplasmic domain of alpha1 as well as alpha2 isoforms of Na,K-ATPase, believed involved in the regulation of Na,K-ATPase activity. Interaction between TCTP and Na,K-ATPase was confirmed by coimmunoprecipitation in yeast and mammalian cells. We also showed, using (86)Rb(+) uptake assay, that overexpression of TCTP inhibited Na,K-ATPase activity in HeLa cells. Northern and Western blotting studies of HeLa cells transiently transfected with GFP-tagged TCTP showed that overexpression of TCTP did not change mRNA and protein levels of Na,K-ATPase. Recombinant TCTP protein purified from an Escherichia coli expression system inhibited purified HeLa cell plasma membrane Na,K-ATPase in a dose-dependent manner. Using deletion analysis, we also found that the C-terminal 102-172-amino-acid region of rat TCTP that contains the TCTP homology region 2 is essential for its association with, and inhibition of, Na,K-ATPase.
Jung
Jaehoon
J
College of Pharmacy, Center for Cell Signaling Research and Division of Molecular Life Sciences, Ewha Woman's University, Seoul 120-750, Korea.
Kim
Moonhee
M
Kim
Min-Jeong
MJ
Kim
Jinyoung
J
Moon
Jiae
J
Lim
Jae-Su
JS
Kim
Miyoung
M
Lee
Kyunglim
K
D014408:Biomarkers, Tumor / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D017434:Protein Structure, Tertiary; D012413:Rubidium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D000090324:Tumor Protein, Translationally-Controlled 1; D015003:Yeasts / Q000378:metabolism
D014408:Biomarkers, Tumor; C000715647:TPT1 protein, human; C000715649:Tpt1 protein, rat; D000090324:Tumor Protein, Translationally-Controlled 1; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium