Figure 9. Hsp40 increases the CSPα stimulation of GTPase activity of Gα_s.

(A) Soluble full length Hsp40, CSPα, SGT and Hsc70 were mixed with γ-[³²P]GTP (1 μCi) prior to the addition of 0.3 µM Gα_s. The amount of released ³²P was measured as counts/min after incubation of the reaction mixture for 30 min at 25°. p values for two-tailed unpaired t test (95% confidence interval) were 0.7344 (*) and 0.0023 (**), respectively. n = 6. (B) Differentiated CAD cells were transfected with CSPα and heat shocked at 42°C for 40 mins. Cells were allowed to recover 5 hrs prior to treatment with 50 µM isoproterenol+50 µM IBMX for 15 min where indicated. Western analysis was carried out and the membrane probed with anti-phospho-synapsin antibody in TBS-BSA-Tween 20. For phosphosynapsin the pixel values from left to right were (control)132, (Iso)2422, (CSPα)7528, (CSPα+Iso)10146, (control&heat shock)3543, (Iso+heat shock)8910, (CSPα+heat shock) 3414, (CSPα+Iso+heat shock) 5206.