J. Biol. Chem., Vol. 255, Issue 24, 11644-11647, 12, 1980

Octopus calmodulin. Structural comparison with bovine brain calmodulin

KB Seamon and BW Moore

A protein previously isolated from octopus optic lobe is shown to have the biochemical characteristics of a calmodulin-like protein. The amino acid composition of the octopus calmodulin is similar to that of another sea invertebrate calmodulin, from Renilla reniformis, in that both contain a single residue of tyrosine which distinguishes them from the vertebrate calmodulins which contain two tyrosines. The 1H NMR spectra of the octopus calmodulin and bovine brain calmodulin are compared in their apo- and calcium-saturated conformations. A comparison of these spectra indicates that the single tyrosine of the octopus calmodulin is in a structurally homologous position to tyrosine- 138 of bovine brain calmodulin. 1H NMR and UV difference spectroscopy also demonstrate that the solution conformations of the apo- and calcium-saturated forms of octopus calmodulin are very similar to those of bovine brain calmodulin. It is concluded that both proteins undergo similar calcium-induced changes in tertiary structure, which result in near identical solution conformations.
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