Figure 3.
Constitutively phosphorylated mutant, Cx45.6(S364D), was resistant to the cleavage by caspase-3 as compared to wild type Cx45.6. Exogenous wild type (WT) Cx45.6 (lanes 1 and 2) and Cx45.6 single phosphorylation site mutants, Cx45.6(S364D) (lanes 3 and 4) were expressed in CEF cells through retroviral infection. Crude membranes isolated from those infected cultures were treated in the absence (lanes 1 and 3) and presence (lanes 2 and 4) of caspase-3 in vitro at 37°C for 6 h. Arrows indicate the cleaved fragments. The protein band intensity was measured by densitometry and the intensity ratio of truncated versus full-length Cx45.6 was calculated (lower panel). (n = 3).