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Two cell lines transformed with temperature sensitive retroviruses were examined for: their ability to grow in low Ca2+ medium, their calmodulin levels and changes in calmodulin acceptor proteins. Both cell lines grow in low Ca2+ medium at the permissive temperature 34 degrees C while both lines did not replicate at the non-permissive temperature 39 degrees C. The NRKLA23 cells have nearly twice as much calmodulin at the permissive temperature than they do at the non-permissive temperature while the 6M2 cells have an equal amount of calmodulin at both temperatures. Both cell lines exhibit changes in the calmodulin acceptor proteins going from the permissive to the non-permissive temperature. We suspect that the changes in the calmodulin acceptor proteins may be involved in the altered Ca2+-sensitivity of growth in the cells going from the permissive to non-permissive temperature.

The 30 kDa calcimedin was found to bind directly to phenyl-Sepharose in a calcium dependent manner similar to calmodulin. The 30 kDa calcimedin was also found to bind to and inhibit DNase I. This calcium-dependent binding was exploited to develop a two-step purification scheme for this calcimedin. In addition, affinity-purified antibodies to the 30 kDa calcimedin were used to examine its tissue distribution. The highest levels were found in lung, trachea and diaphragm while the lowest levels of the 30 kDa calcimedin were found in brain and skeletal muscle.

Annexins are a family of calcium/phospholipid binding proteins sharing strong sequence similarities. A site-directed affinity-purified antibody was produced against the consensus peptide, K A M K G L G T D E. This antibody recognizes all six annexin proteins in the purified state and in total-protein tissue extracts. The antibody should prove useful in identifying functional domains of this protein family.