Identification of HSP70-2 as a resident of the export compartment.

The malarial parasite remodels the host erythrocyte following invasion. Well-known examples are adhesive proteins inserted into the host erythrocyte membrane, which function as virulence factors. The modification of the host erythrocyte may be mediated by a specialized domain of the endoplasmic reticulum, or export compartment (PEC). Previously, monoclonal antibodies recognizing the PEC were generated and one of these monoclonal antibodies recognize a 68 kDa parasite protein. In this study, the 68 kDa protein was affinity purified and analyzed by peptide mapping using mass spectrometry. The results demonstrate that the 68 kDa protein is the homolog of the endoplasmic reticulum resident HSP70 called HSP70-2. This finding is consistent with the PEC being a domain of the endoplasmic reticulum and suggests a role for HSP70-2 in the export of proteins into the host erythrocyte.