B. Freyer et al., ISOLATION AND CHARACTERIZATION OF CDNA CLONES ENCODING A 32-KDA DENSE-GRANULE ANTIGEN OF SARCOCYSTIS-MURIS (APICOMPLEXA), Parasitology research, 84(7), 1998, pp. 583-589
A monoclonal antibody (2F4) directed against a 32-kDa dense-granule an
tigen of Sarcocystis muris cyst merozoites (bradyzoites) was used to s
creen a lambda ZAP cDNA expression library. A clone with an insert of
1.4 kb in length (DG 32/1) was isolated. A fusion protein derived from
bacteria harbouring the recombinant plasmid DG 32/1 reacted with mono
clonal antibody (mAb) 2F4. Southern blot hybridization suggests that t
he gene is present as a single copy. On Northern blots, a single mRNA
species of 1.8 kb was detected by a cDNA-derived probe. In addition, w
e isolated a full-length clone (DG 32/PH1) by screening the cDNA libra
ry with a non-radioactive-labelled cDNA probe. The nucleotide sequence
of DG 32/PH1 comprises 1.57 kb. It contains an open reading frame of
882 bp with a coding capacity of approximately 32 kDa. The hypothetica
l polypeptide consists of a putative N-terminal signal peptide and the
mature protein sequence. The occurrence of an N-terminal signal seque
nce is consistent with the observation that the 32-kDa protein of S. m
uris is secreted from the dense granules.