Characterization of the protein contents of rhoptries and dense granules of Toxoplasma gondii tachyzoites by subcellular fractionation and monoclonal antibodies.

A subcellular fractionation procedure has been established to isolate the rhoptries of Toxoplasma gondii tachyzoites on a self-generating Percoll gradient. The rhoptry fraction also contains dense granules. Monoclonal antibodies have been raised against the fraction and used to identify major proteins in the organelles by immunoelectron microscopy and Western blotting. Six major rhoptry proteins (60.5 kDa, Pi 5.8; 55, 57, 59, 60 kDa, all of Pi over 8; 42 kDa, Pi 4.8) and 3 dense granule proteins (30 kDa; 28kDa, Pi 7.5; 27 kDa, Pi 4.5) together with 5 other proteins of 57, 90, 120, 168, 220 kDa that have been located in the rhoptry area by indirect immunofluorescence have been identified.