An immunological and biochemical comparison of 67 kDa calcimedin and 67 kDa calelectrin.

The 67 kDa calcimedin is a Ca2+-binding protein isolated from several muscle tissues. A recent report [Morse & Moore (1988) Biochem. J. 251, 171-174] indicated that the 67 kDa calcimedin is distinct from 67 kDa calelectrin, which is purified from various non-muscle cells. In the present study we have purified the 67 kDa protein from bovine aorta (i.e. 67 kDa calcimedin) and liver (i.e. 67 kDa calelectrin) and compared them by immunological and biochemical criteria. The aorta calcimedin is identical with the liver calelectrin by the following criteria. (1) The calcimedin co-electrophoresed with the calelectrin on SDS/5-15%-(w/v)-linear-gradient polyacrylamide gels. (2) The two proteins selectively cross-reacted with a chicken gizzard calcimedin antibody. (3) An antibody raised against the bovine aorta calcimedin also recognized the bovine liver calelectrin. (4) One-dimensional peptide maps of the two proteins revealed no significant difference. (5) The calcimedin appeared to have an amino acid composition essentially the same as that of the liver calelectrin. (6) The amino acid sequences of the calcimedin fragments were identical with those of the calelectrin fragments.