Abstract
Procedures were developed for the purification of calmodulin from the eggs and from the sperm of the sea urchin Strongylocentrotus purpuratus and Arbacia punctulata. Two forms of calmodulin were isolated from A. punctulata eggs, one from each of the other three sources. All five calmodulins are similar to vertebrate calmodulin as judged by their activation of bovine brain cyclic nucleotide phosphodiesterase, calcium-dependent interaction with troponin I and with chloropromazine, increased anode mobility on sodium dodecyl sulfate gels in the presence of calcium, cross-reactivity with anti-vertebrate calmodulin antibodies and amino acid compositions including the presence of a single residue of trymethyllysine. The two forms of calmodulin from A. punctulata eggs, calmodulin A and calmodulin B, can be distinguished from one another on the basis of DEAE-cellulose chromatography, amino acid analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence or absence of calcium and competitive radioimmunoassays. There is no evidence that either form is a proteolytic product of the other.
Highlights
Urchin Strongylocentrotus purpuratus and Arbacia It was reported previously (Burgess et al, 1980) that calpunctulata
Purification of Calmodulin from S. purpuratus EggsPurifkation schemes for calmodulin fromS. purpuratus eggs similar to that one described by Head et al (1979) or that described under "Materials and Methods" of this paper for A . punctulata eggs were used initially
The ethanol precipitation procedure described by Charbonneau and Cormier (1979) wastried because the density of the protein solution decreases as theconcentration of prscipitant, ethanol, is increased. This procedure proved to be satisfactory for S. purpuratus eggs
Summary
T w o formsofcalmodulin were isolated modulin isolated from S. purpuratus sperm is very similar to from A. punctulata eggs, one from each of the other bovine brain calmodulin as judged by its interaction with three sources. Calmodulin is the prototype of calcium-modulated proteins. It is present inthe cytosol of all (or most) cells of all (or most) eukaryotes (see review by Klee et al, 1980; New York Academy of Sciences, Vol 356, 1980). Of 148 residues, there are at most only seven differences in amino acid sequence between calmodulin from bovine brain(Watterson et al, 1980b) and that from the marine invertebrate, Renilla reinformis (Jamieson et al, 1980).This is consistent with the fact that in contrast to the specialized roles of other calciummodulated proteins, calmodulin interacts in a calcium-dependent and -specific manner with at least 15 different proteins. (ethy1enedinitrilo)tetraacetic acid; CAPP, 2-chloro-l0-(3-aminopropyl) phenothiazine hydrochloride; EGTA, [ethylenebis(oxyethylenenitrilo)]tetraacetic acid
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