Biochem Biophys Res Commun. 2007 Sep 19; [Epub ahead of print]
Toxoplasma gondii possesses a receptor for activated C kinase ortholog
Moran JM, Smith SS, Hager KM
Receptor for activated C kinase 1 (RACK1) has been implicated in multiple protein-protein interactions including functioning as a scaffolding protein for signaling molecules. We report the cloning and cellular localization of a RACK1 ortholog (TgRACK1) in the opportunistic pathogen Toxoplasma gondii. The full-length transcript possesses a predicted ORF of 966bp and codes for a protein of approximately 35kDa molecular weight. Molecular analysis of TgRACK1 reveals the presence of seven WD40 repeat motifs. TgRACK1 was tagged with a FLAG epitope and stably expressed in RH parasites. FLAG-TgRACK1 localizes to the parasite cytoplasm and nucleus. Immunoprecipitation (IP) of FLAG-TgRACK1 from highly purified extracellular parasites followed by immunoblot analysis reveals an interaction between TgbetaCOP and FLAG-TgRACK1. This is the first demonstration of an interaction between a betaCOP subunit and the RACK1 protein. This result is of interest given that a signaling event precedes protein secretion and parasite invasion.