Fig. 5.

The extended C-terminal tail of non-amniote sarcopterygians inhibits the CO₂ sensitivity of Cx26 hemichannels. a Comparison of the C-terminal tail of Cx26 in amniote and non-amniote vertebrates. b Removal of the C-terminal tail of Xenopus and substitution of PV for final two residues (xtCx26ΔPV) gives good expression of the modified Cx26 and demonstrates gain of CO₂ sensitivity. Addition of the Xenopus C-terminal tail to human Cx26 (hCx26 + XenCT) causes loss of CO₂ sensitivity. In Latimeria, a copy of the Cx26 gene lacking the C-terminal tail is CO₂ sensitive. 1. XP_014348762.1, 2. ENSLACG00000007568. c Summary data showing the increase in dye loading with the 55 mmHg PCO₂ and zero Ca²⁺ stimuli (expressed as the change in pixel intensity from control 35 mmHg PCO₂). Box and whisker plots: box, first and third quartiles; horizontal line, median; whiskers, the furthest point that lies no more than 1.5 times the interquartile range from the median. Each point represents the median change in pixel intensity from the control saline (35 mmHg PCO₂) from an independent transfection. Scale bar 20 µm