INVESTIGATION OF CALCIUM-BINDING PROPERTIES OF MTS-1 PROTEIN AND ITS RECOMBINANT ANALOG BY THE FLUORESCENT-PROBE FURA-2

A procedure based on the ability of metastasin (Mts-1) to competitivel y inhibit the formation of Fura-2 complexes with Ca2+ is described. Mt s-1 has been shown to reversibly inhibit the complex formation between Fura-2 and Ca2+. The efficiency of natural Mts-1 isolated from cells of the CSML-100 line and of its recombinant analog on the formation of the Fura-Ca2+ complex is different. The inhibition constant K-i for t he native protein is equal to 2.4 mu M, and that for the recombinant f orm is 8.5 mu M. Data obtained are suggestive of posttranslational mod ification of Mts-1 in cells under in vivo conditions.