Calcyclin-Like Protein from Ehrlich Ascites Tumour Cells - Ca2+ -Binding Properties, Distribution and Target Protein

Abstract

We have purified to homogeneity a 10.5 kDa Ca2+-binding protein from Ehrlich ascites tumour (EAT) cells (Kuznicki & Filipek, 1987). This protein differs from S-100 protein, calbindin 9k, parvalbumin and on comodulin by several criteria such as electrophoretic mobility in SDS- or urea-polyacrylamide gels, amino acid composition, and lack of cross-reactivity with the antibodies specific to these Ca2+-binding proteins. Recently, we found that the partial amino acid sequence of the 10.5 kDa Ca2+- binding protein from EAT cells is homologous to that of human calcyclin, and therefore we call the mouse protein a calcydin-like protein (Kuznicki et al., 1989a). Calcyclin is the name given to the growth factor-inducible gene (Calabretta et al., 1986a; 1986b). It has been suggested that calcyclin protein is involved in the control of cell proliferation and may bind Ca2+, as deduced from nucleotide sequence of the gene. To our best knowledge nobody has so far studied the protein itself.