The plastid organelle of malarial and other apicomplexan parasites contains
ribosome-like particles as well as a genome dedicated largely to specifyin
g components of a protein expression system. We have identified plastid rib
osomes using hybridization studies and show that in erythrocytic stages of
Plasmodium falciparum a subset of polysomes carries plastid-specified rRNAs
and mRNA, supporting the idea that protein synthesis is active in the plas
tid.