Rodent sodium potassium-atpase alpha-1 and alpha-3 catalytic subunit regulation involves conventional protein kinase c subtypes

Ouabain-sensitive rubidium transport in cultured OK cells expressing rodent Na+, K+-ATPase (Na-K pump) á1 or á3 isoforms were used to measure intracellular signaling and structural variations involved in transport responses. Since kinetic differences between isozymes seem to be of little functional consequence, more insight into Na-K pump subunit signaling diversity and its physiological relevance was sought by determining their interaction with regulatory proteins such as protein kinase C (PKC) which also exists in multiple forms. The evaluations began with comparing the effects of phorbol ester as a PKC agonist and a conventional PKC inhibitor on rodent á1 and á3. Cytoskeletal framework integrity was then examined as a requirement for the possible secretion or removal of functional Na-K pump units through intracellular vesicle trafficking. This study found evidence in favor of the conventional PKC subfamily being responsible for ouabain-inhibitable transport increases in cells expressing rodent á3 Na-K pump. Also, á3 appeared to have a greater sensitivity to the conventional PKC signaling pathway than á1. As for the cytoskeletal examination, the pharmacological approach used lead to noisy and unreliable signals. Biotinylation, real-time visualization, such as GFP labeling, or immunolabeling are alternative methods recommended to provide more conclusive evidence for rodent á3* Na-K pump trafficking.