Depletion of Ca2+ stores triggers PMCA and
NHERF-2 trafficking to the cell membrane. HT-29 cells were exposed to CPA
(5 μm) in the absence of extracellular Ca2+.
A, representative Fura-2 tracing showing changes in
[Ca2+]i following the addition of CPA (5
μm) to the bathing solution at 20 s. B, representative
Western blot showing changes in membrane-associated PMCA during exposure to
CPA. C, densitometry showing time-dependent changes in
membrane-associated PMCA during exposure to CPA. Membrane levels of PMCA
peaked to 61 ± 12% (n = 3; **, p <
0.01) above control levels at 120 s and returned to baseline levels by 300 s.
D, representative Western blot showing changes in membrane-associated
NHERF-2 during exposure to CPA. E, densitometry showing changes in
membrane-associated NHERF-2 during exposure to CPA. Membrane levels of NHERF-2
peaked by 180 ± 11% (n = 3; *, p <
0.05; **, p < 0.01; ***, p <
0.001) and returned to resting levels by 300 s. All data are expressed as mean
± S.E.