Ppj. Dunn et al., SEQUENCE, EXPRESSION AND LOCALIZATION OF CALMODULIN-DOMAIN PROTEIN-KINASES IN EIMERIA-TENELLA AND EIMERIA-MAXIMA, Parasitology, 113, 1996, pp. 439-448
We have isolated and sequenced cDNA clones from Eimeria tenella and Ei
meria maxima which encode proteins that share homology with a recently
described family of calmodulin-domain protein kinases. The primary se
quence data show that each of the protein kinases can be divided into
2 main functional domains-an amino-terminal catalytic domain typical o
f serine/threonine protein kinases and a carboxy-terminal domain homol
ogous to calmodulin, which is capable of binding calcium ions at 4 'EF
-hand' motifs. Expression of the E. tenella calmodulin-domain protein
kinase (EtCDPK) increased towards the end of oocyst sporulation, as ju
dged by Northern and Western blotting, and indirect immunofluorescent
antibody labelling showed that within a few minutes of adding sporozoi
tes to target host cells in in vitro culture EtCDPK was found to be sp
ecifically associated with a filament-like structure that converges at
the apical end of the parasite. Once the parasite entered the host ce
ll EtCDPK appeared to be left on the host cell membrane at the point o
f entry, indicating a brief yet specific role for this molecule in the
invasion of host cells by. E. tenella.