Identification of the Calcium Binding Sites in Translationally Controlled Tumor Protein

  • Kim, Moon-Hee (College of Pharmacy, Center for Cell Signaling Research and Division of Molecular Life Sciences, Ewha Womans University) ;
  • Jung, Yoon-Wha (College of Pharmacy, Center for Cell Signaling Research and Division of Molecular Life Sciences, Ewha Womans University) ;
  • Lee, Kyung-Lim (College of Pharmacy, Center for Cell Signaling Research and Division of Molecular Life Sciences, Ewha Womans University) ;
  • Kim, Choon-Mi (College of Pharmacy, Center for Cell Signaling Research and Division of Molecular Life Sciences, Ewha Womans University)
  • Published : 2000.12.01

Abstract

Translationally controlled tumor protein (TCTP), also known as IgE-dependent histamine-releasing factor, is a growth-related tumor protein. Although the primary sequence of rat TCTP does not reveal any recognizable $Ca^{2+}$ -binding motif, previous studies have demonstrated that rat TCTP consisting of 172 amino acids is a $Ca^{2+}$ -binding protein. However. the region of TCTP required for $Ca^{2+}$ interaction has not been mapped to the molecule. Here, we reported that the $Ca^{2+}$ binding region of TCTP which was mapped by using a combination of deletion constructs of rat TCTP and $^{45}Ca^{2+}$-overlay assay. was confined to amino acid residues 81-112. This binding domain did not show any peculiar loop of calcium- binding motif such as CaLB domain and EF hand motif and it seems to be constituted of random coil regions neighboring the a helix. Thus, our data confirm that TCTP is a novel family of $Ca^{2+}$ -binding protein.

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