Fig. 1.

Ht31 increases PKA activity without elevation of cAMP. a The sequences of Ht31 and Ht31P. Ht31 and Ht31P are stearated at the N-terminus to increase cell membrane permeability. b The increase in PKA activity by Ht31. Ht31P (50 µM), Ht31 (50 µM), or dDAVP (1 nM) was added to the basolateral side of the mpkCCD cells for 1 h. Representative blots of three independent experiments are shown. c Dose-response studies of H89. Ht31 (50 µM) or dDAVP (1 nM) was added in the presence or absence of H89 (1–100 µM) for 1 h. The mpkCCD cells were pretreated with H89 for 1 h before Ht31 or dDAVP stimulation. Representative blots of three independent experiments are shown. d No significant elevation of cAMP concentration in response to Ht31. The mpkCCD cells were treated with Ht31P (50 µM), Ht31 (50 µM), or dDAVP (1 nM) for 1 h. Bars are mean values ± SD of three experiments. Asterisk indicates a significant difference compared with control. Tukey, **p < 0.01. e, f The effects of Ht31 on PKA localization and activity. Ht31P (50 µM) or Ht31 (50 µM) was added to the basolateral side of the mpkCCD cells for 1 h. The mpkCCD cells were then incubated with 1% Triton X-100 for 3 min before cell lysis and were divided into a detergent-soluble cytosol fraction and an insoluble membrane fraction (MF). Representative blots of three independent experiments are shown