Fig. 6: IRBIT-dependent dephosphorylation of S²³², S²³³ and/or S²³⁵ affect NBCe1-B activity and activation by IRBIT.

(a, b): The effect of the S²³², S²³³ and/or S²³⁵ mutations on NBCe1-B surface expression and interaction with IRBIT (n=4). (c, d): Current was measured with pipette solution containing 5 mM Cl⁻ and in the presence (+) or absence of IRBIT, as indicated. The cells were transfected with (c) NBCe1-B (gray), NBCe1-B(SSS/AAA) (red), NBCe1-B(SSS/DDD) (blue), NBCe1-A and its AAA and DDD mutants, NBCe1-B(Δ1–95) and its AAA and DDD mutants, (d) S²³²A or S²³²D (red), S²³³A or S²³³D (blue) and S²³⁵A or S²³⁵D (green). The models in (c, d) depict the phosphorylation state of S²³², S²³³ and S²³⁵ for the indicated mutants. * denotes p<0.01 relative to no IRBIT. The numbers in the columns indicate the number of current measurements and the results are given as mean±s.e.m.