title: Analysis of the complete sequence of a muscle calcium-binding protein of Schistosoma mansoni.
abstract: The complete sequence of the cDNA encoding a 20 kDa calcium-binding protein of Schistosoma mansoni (Sm20) has been determined. The predicted amino acid sequence contains 4 EF hand domains but examination of the predicted secondary structure of Sm20, together with the specific residues in each calcium-binding domain, suggests that only 1 EF hand (domain IV) is functional. Sm20 is most homologous to calmodulin, troponin C and the regulatory light-chain of myosin, particularly those of invertebrates. However, troponin C and the regulatory light-chain of myosin can be distinguished from Sm20 by size and by their differential levels of expression during the life-cycle. Sm20 also appears to be distinct from calmodulin but may be functionally equivalent to the soluble sarcoplasmic calcium-binding proteins of molluscs and crustacea which may act as a reservoir for calcium in muscle. Sm20 is encoded by a small multi-gene family whose members are clustered within a 15 kb region of the genome. A 20 kDa antigen, cross-reactive with Sm20, is expressed in Schistosoma haematobium, Fasciola hepatica and Paragonomus mexicanus.
authors.affiliation: Department of Pathology, University of Cambridge.
authors.forename: T J
authors.initials: TJ
authors.lastname: Stewart
authors.forename: A L
authors.initials: AL
authors.lastname: Smith
authors.forename: J C
authors.initials: JC
authors.lastname: Havercroft
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000947:Antigens, Helminth; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D002147:Calmodulin / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D005260:Female; D015801:Helminth Proteins / Q000737:chemistry* / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D005810:Multigene Family; D015879:Myosin Subfragments / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D016366:Open Reading Frames; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D015183:Restriction Mapping; D012550:Schistosoma mansoni / Q000737:chemistry* / Q000235:genetics; D014336:Troponin / Q000737:chemistry
chemical_list: D000947:Antigens, Helminth; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D015801:Helminth Proteins; D015879:Myosin Subfragments; D012333:RNA, Messenger; C074267:Sm20 protein, Schistosoma mansoni; D014336:Troponin; D004247:DNA