Trypanosoma cruzi: stage expression of calmodulin-binding proteins.

The subcellular distribution of calmodulin-binding proteins in three life stages of Trypanosoma cruzi was analyzed by a [125I]calmodulin gel overlay procedure under conditions where proteolysis was kept to a minimum. It was found that T. cruzi contains a complex profile of calcium-dependent calmodulin-binding proteins and that several of these polypeptides were differentially expressed at specific stages of development. The majority of these stage-specific polypeptides was found in the particulate fractions of the replicative stages of the parasite, i.e., epimastigote and amastigote. These studies suggest that calcium and calmodulin may play an important central role in the growth and differentiation of this parasite. We have also assessed the calmodulin content of the various life stages by immunoblot analysis. These studies identified a 14-kDa immunoreactive peptide present at equivalent levels in epi-, trypo-, and amastigote stages (extracellular).