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.

This paper is dedicated to the memory of Professor Witold Drabikowski who organized the First International Symposium on Calcium Binding Proteins held in Jablonna, Poland, in 1973.