FIGURE 5.
The relative amounts of β- and γ-subunits in membrane ENaC are the same. Scatter plot of eCFP versus eYFP fluorescence emissions collected with TIRF microscopy from cells coexpressing eCFP-βENaC + eYFP-γENaC and untagged αENaC (A) and eCFP-γENaC + eYFP-βENaC and untagged αENaC (C). Solid red lines are the best-fit linear regression lines (m = fluorescence intensity ratio for panels A and C, which are k1 and k2); black dashed lines predict subunit relations at the indicated stoichiometry; red, blue, and green circles represent data points from cells transfected with equal amounts of eCFP- and eYFP-tagged subunit and those with twice and three times as much eCFP- versus eYFP-tagged subunit, respectively. Scatter plots of the quotient of eCFP/eYFP fluorescence emissions from panel A (B) and panel C (D) as a function of the relative eCFP- to eYFP-tagged subunit expression level.