TY  - JOUR
A1  - Voss, Martin
A1  - Schmidt, Ruth
A1  - Walz, Bernd
A1  - Baumann, Otto
T1  - Stimulus-induced translocation of the protein kinase A catalytic subunit to the apical membrane in blowfly salivary glands
N2  - Secretion in blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT), which activates the InsP(3)/Ca2+ pathway and the cAMP/protein kinase A (PKA) pathway in the secretory cells. The latter signaling cascade induces the activation of a vacuolar H+-ATPase on the apical membrane. Here, we have determined the distribution of PKA by using antibodies against the PKA regulatory subunit-II (PKA-RII) and the PKA catalytic subunit (PKA-C) of Drosophila. PKA is present in high concentrations within the secretory cells. PKA-RII and PKA-C co-distribute in non-stimulated glands, being enriched in the basal portion of the secretory cells. Exposure to 8-CPT-cAMP or 5-HT induces the translocation of PKA-C to the apical membrane, whereas the PKA-RII distribution remains unchanged. The recruitment of PKA-C to the apical membrane corroborates our hypothesis that vacuolar H+-ATPase, which is enriched in this membrane domain, is a target protein for PKA.
Y1  - 2009
UR  - http://www.springerlink.com/content/100524
U6  - https://doi.org/10.1007/s00441-008-0673-x
SN  - 0302-766X
ER  - 
TY  - JOUR
A1  - Dames, Petra
A1  - Zimmermann, Bernhard
A1  - Schmidt, Ruth
A1  - Rein, Julia
A1  - Voss, Martin
A1  - Schewe, Bettina
A1  - Walz, Bernd
A1  - Baumann, Otto
T1  - cAMP regulates plasma membrane vacuolar-type H+-ATPase assembly and activity in blowfly salivary glands
N2  - Reversible assembly of the V0V1 holoenzyme from V-0 and V-1 subcomplexes is a widely used mechanism for regulation of vacuolar-type H+-ATPases (V-ATPases) in animal cells. in the blowfly (Calliphora vicina) salivary gland, V- ATPase is located in the apical membrane of the secretory cells and energizes the secretion of a KCl-rich saliva in response to the hormone serotonin. We have examined whether the CAMP pathway, known to be activated by serotonin, controls V-ATPase assembly and activity. Fluorescence measurements of pH changes at the luminal surface of isolated glands demonstrate that CAMP, Sp-adenosine-3',5'-cyclic monophosphorothioate, or forskolin, similar to serotonin, cause V-ATPase-dependent luminal acidification. In addition, V-ATPase-dependent ATP hydrolysis increases upon treatment with these agents. Immunofluorescence microscopy and pelleting assays have demonstrated further that V, components become translocated from the cytoplasm to the apical membrane and V-ATPase holoenzymes are assembled at the apical membrane during conditions that increase intracellular cAMP. Because these actions occur without a change in cytosolic Ca2+, our findings suggest that the cAMP pathway mediates the reversible assembly and activation of V-ATPase molecules at the apical membrane upon hormonal stimulus
Y1  - 2006
UR  - http://www.pnas.org/
U6  - https://doi.org/10.1073/pnas.0600011103
SN  - 0027-8424
ER  -