Amino acid sequence of squid troponin C.
The complete amino acid sequence of squid Todarodes pacificus troponin C (TnC), which was shown to bind only 1 mol Ca(2+)/mol, was determined by both the Edman and cDNA methods. The squid TnC is composed of 147 amino acids including an unblocked Pro at the N-terminus and the calculated molecular weight is 17003.9. Among the four potential Ca(2+)-binding sites, namely sites I-IV from the N-terminus, only site IV completely satisfied the consensus amino acid sequence for the active Ca(2+)-binding loop. This indicates that squid TnC possesses a single Ca(2+)-binding site at the site IV as scallop TnCs [Nishita et al., J. Biol. Chem. 269 (1994) 3464-3468; Ojima et al., Arch. Biochem. Biophys. 311 (1994) 272-276). The sequence homology of squid TnC to TnCs of scallop, arthropods, and rabbit was 61%, 31-38%, and 31%, respectively. In the sequence of the central D/E-helix region of squid and scallop TnCs, a deletion of three amino acids was required to maximize the homology with the other TnCs.
Ojima
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Laboratory of Biochemistry and Biotechnology, Graduate School of Fisheries Science, Hokkaido University, Hakodate, 041-8611, Hokkaido, Japan. ojima@fish.hokudai.ac.jp
Ohta
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Nishita
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D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D049832:Decapodiformes; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D015723:Gene Library; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013997:Time Factors; D019209:Troponin C / Q000737:chemistry* / Q000235:genetics*
D000596:Amino Acids; D018076:DNA, Complementary; D010455:Peptides; D019209:Troponin C; D002118:Calcium