Fig. 3

Regulation of cytosol–membrane PKA subunits translocation by pre- and postsynaptic activities. A The purity of the subcellular fractionation was validated by western blotting of the fraction-specific proteins GAPDH for cytosol and Na+/K+-ATPase for membrane. B1 Effect of presynaptic stimulus and postsynaptic muscle contraction on the ratio of membrane (mb)/cytosol (cyt) fractions of the PKA subunits. The diagrams are graphic representations that collectively show the patterns of changing of the ratio mb/cyt fractions of the PKA subunits during presynaptic activity (Ctrl versus ES—blue), contraction abolished by µ-conotoxin GIIIB, and contraction (ES versus ES + C—red). Data are expressed relative to control (black line) (mean). B2 Graphical representation of the results. C–H Western blot analysis and data quantification of catalytic (Cα, Cβ) and regulatory (RIα, RIβ, RIIα, RIIβ) PKA subunits in the cytosol and membrane fractions of the diaphragm muscle. Protein levels are studied after treatment with presynaptic stimulation without contraction—Ctrl versus ES and with muscle contraction—ES versus ES + C. Data are expressed relative to control (mean ± SD). *p < 0.05, **p < 0.01, and ***p < 0.001 versus the corresponding control. Cα/β, protein kinase A catalytic subunit α/β; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; RIα/RIβ/RIIα/RIIβ, protein kinase A regulatory subunits Iα/Iβ/IIα/IIβ; cyt, cytosol; mb, membrane