title: Characterization of cDNA clones encoding a major microneme antigen of Sarcocystis muris (Apicomplexa) cyst merozoites.
abstract: Two monoclonal antibodies directed against a microneme antigen of Sarcocystis muris cyst merozoites (16/17 kDa band doublet) were used to isolate cDNA clones from a lambda ZAP expression library. Restriction analysis revealed that the inserts were highly similar, with sizes ranging between 1.8 and 2.3 kb. In addition, a full-length cDNA insert of 2.6 kb was obtained by hybridization screening. On Northern blots, a single mRNA species of 2.7 kb was detected by a cDNA-derived probe. Southern blot hybridization suggests that the gene is present as a single copy. The nucleotide sequence of the full-length clone contains a single reading frame with a coding capacity of 26.5 kDa. The hypothetical polypeptide consists of a putative N-terminal signal peptide followed by a hydrophilic domain of unknown function, and the mature protein sequence. After purifying the 16/17 kDa antigen from cyst merozoites, a partial N-terminal amino acid sequence was obtained. Thus, the identity of the cDNA sequence was confirmed. The deduced sequence of the mature protein is predominantly hydrophilic and rich in cysteine (8.7%). Database searching suggested weak homologies of the hypothetical polypeptide to plasma kallikrein, tenascin and blood coagulation factors.
authors.affiliation: Arbeitsgruppe Molekulare Genetik, Ruhr-Universität Bochum, Germany.
authors.forename: K H
authors.initials: KH
authors.lastname: Eschenbacher
authors.forename: H
authors.initials: H
authors.lastname: Klein
authors.forename: I
authors.initials: I
authors.lastname: Sommer
authors.forename: H E
authors.initials: HE
authors.lastname: Meyer
authors.forename: R
authors.initials: R
authors.lastname: Entzeroth
authors.forename: H
authors.initials: H
authors.lastname: Mehlhorn
authors.forename: W
authors.initials: W
authors.lastname: Rüger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics*; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D015183:Restriction Mapping; D012522:Sarcocystis / Q000235:genetics* / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D018076:DNA, Complementary; D016054:DNA, Protozoan; D015800:Protozoan Proteins