Characterization of a calcium-modulated protein from transformed chicken fibroblasts

A calcium-modulated protein has been isolated from secondary cultures of virus transformed chicken embryo fibroblasts and has been characterized in terms of its physical, chemical, and functional properties. These properties demonstrate that this protein is a calmodulin and distinguish it from other calcium-modulated proteins found in various muscle and non-muscle tissues. In addition, this transformed cell calmodulin has been shown to be indistinguishable in both structure and function from normal cell calmodulins isolated from chicken gizzard and brain. A novel change in the electrophoretic behavior of these calmodulin preparations that is dependent on sample history has been observed. These alterations may be the basis for previous reports of tissue specific differences in calmodulin and for some of the differences occasionally observed in peptide maps of calmodulins.