A novel EF-hand Ca(2+)-binding protein from abdominal muscle of crustaceans with similarity to calcyphosine from dog thyroidea.
The amino acid sequence of a novel EF-hand Ca(2+)-binding protein from the abdominal muscle of the crayfish, Orconectes limosus, has been elucidated by tandem mass spectrometry and automated Edman degradation. The name CCBP-23 (23-kDa crustacean Ca(2+)-binding protein) is proposed. The protein can also exist as a disulfide-linked homodimer. The sequence of the monomeric form spans 200 residues with an acetylated N-terminal Ser and reveals four EF-hand domains. The 174-mass-unit difference between the calculated average molecular mass of 22,669.6 Da deduced from the sequence and the obtained electrospray ionization mass spectroscopy (ESI-MS) mass of 22,844 Da has not yet been explained. Partial sequence analysis (137 residues) of CCBP-23 from the lobster, Homarus americanus, showed a sequence identity of 74% with the crayfish protein. Homology searches revealed a 44% sequence identity of CCBP-23 from crayfish to calcyphosine, a Ca(2+)-binding protein from dog thyroidea (Lefort et al., 1989). Although CCBP-23 also shows a 44% identity to R2D5 antigen (Nemoto et al., 1993), we believe that both proteins represent two distinct subgroups within the family of EF-hand proteins.
Institute of Zoophysiology, University of Bonn, Germany.
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A
Sauter
W
W
Staudenmann
G J
GJ
Hughes
C W
CW
Heizmann
D000595:Amino Acid Sequence; D000818:Animals; D003400:Astacoidea / Q000737:chemistry; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification; D004285:Dogs; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry* / Q000302:isolation & purification; D008121:Nephropidae / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013961:Thyroid Gland / Q000737:chemistry*
C059605:CAPS protein, human; C091916:CCBP-23 protein, Orconectes limosus; D002135:Calcium-Binding Proteins; D009124:Muscle Proteins