Translationally controlled tumor protein interacts with the third cytoplasmic domain of Na,K-ATPase α subunit and inhibits the pump activity in HeLa cells

Jaehoon Jung, Moonhee Kim, Min Jeong Kim, Jinyoung Kim, Jiae Moon, Jae Su Lim, Miyoung Kim, Kyunglim Lee

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80 Scopus citations

Abstract

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 α1 as well as α2 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 86Rb+ 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.

Original languageEnglish
Pages (from-to)49868-49875
Number of pages8
JournalJournal of Biological Chemistry
Volume279
Issue number48
DOIs
StatePublished - 26 Nov 2004

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