46th Annual Conference of the American Society for Cell Biology
San Diego, CA
polycation, receptor, Paramecium
Unicellular eukaryotes are complex systems, performing all the tasks needed for survival within the context of a single cell. Protozoans, such as Tetrahymena and Paramecium, use chemosensory systems to detect food and to avoid predation.
Both Tetrahymena and Paramecium have been used as models for studying chemorepellents. Lysozyme, ATP, and GTP have been found to have chemorepellent activity in both ciliates. In Tetrahymena, several PACAP isoforms have been shown to bind to the same receptor as lysozyme, indicating that this receptor may be a more general “polycation receptor” (Keedy et al., 2003). The polycation receptor in Tetrahymena appears to be a Gprotein linked receptor which activates adenylyl cyclase and phospholipase C (Keedy et al., 2003).
The lysozyme receptors have been affinity purified from both Paramecium and Tetrahymena. The molecular weight of the Tetrahymena protein is approximately 42 kD, while the molecular weight of the Paramecium protein is approximately 58 kD (Kuruvilla and Hennessey, 1998).
In our current study, we examined the hypothesis that Paramecium have a polycation receptor similar to that of Tetrahymena. We found that although both organisms bind similar ligands, there are multiple differences between the two pathways (
Robinette, E.D., Kuruvilla, H. G. Characterizing the polycation receptor of Paramecium. Mol. Biol. Cell 17 (supplement), Presented at the 46th Annual ASCB Conference, December, 2006.