2000 Global Researcher Conference Proceeding
March 10 - 12, 2000
|Conference:||2000 Global Researcher Conference|
|Title:||The stoichiometry of phosphorylated and non-phosphorylated monomers in an aquaporin-2 tetramer determines its subcellular localization|
|Authors:||Kamsteeg, Erik-Jan; Heijnen, I.; van Os, Carel; Deen, Peter M.T.|
|Institution:||University of Nijmegen|
In order for AQP2 to leave their intracellular transport sacs and get to the apical cell membrane, it must first undergo phosphorylation, a process that connects it to a phosphate group. Nonetheless, phosphorylated AQP2 (p-AQP2) has been detected inside vesicles (the transport sacs) as well as the apical membrane. Since AQP2 is made up of a union of four like parts, the researchers speculated that the number of parts comprising the AQP2 that get phosphorylated might be the determining factor in its movement from the vesicle to the apical membrane.
The researchers injected two different AQP2 mutants into laboratory cell cultures. One mutant acted like non-phosphorylated AQP2 (non-p-AQP2); the other acted as p-AQP2. The non-p-AQP2 mutant is retained in the cell, never traveling to the apical membrane; the mutant p-AQP2 does. Also, neither of the mutants was made up of four like parts. Subsequent testing suggests that at least three out of the four parts that comprise an AQP2 must undergo phosphorylation to be able to move from the vesicles to the apical membrane. The researchers further suggest that the chemical changes of phosphorylated and non-phosphorylated sub-units of other channel proteins effect the activity of sub-cellular localization of the proteins they comprise.