Human homolog of mouse tescalcin associates with Na+/H+ exchanger type-1

A novel regulatory protein, tescalcin (TSC), recently isolated from mouse e mbryonic testes, has been implicated in gonadal differentiation. Employing the yeast two-hybrid system with the Na+/H+ exchanger type-1 (NHE1) carboxy terminal domain as a bait we have identified a novel NHE1-associated protei n of 214 amino acid residues representing the human homolog of mouse TSC (9 6.7% identity). Co-precipitation experiments demonstrated the interaction o f human TSC with NHE1 in vitro and in vivo, and Ca-45(2+) overlay assay rev ealed, that TSC binds Ca2+. Immunofluorescence studies indicated that TSC i s prominent in cellular lamellipodia where it colocalizes with NHE1. Abunda nt expression of TSC mRNA in the heart suggests that TSC may play important role(s) in concert with NHE1 in cardiac tissues. (C) 2001 Federation of Eu ropean Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.