Fig. 2.

SPCA1-Q747A enhances the GPP130 Mn²⁺ response. (A) HeLa cells were transfected with HA-tagged SPCA1-WT or mutated constructs and 24 h later imaged to detect HA and GPP130. GPP130 was degraded in cells transfected with SPCA1-Q747A but not WT or the double mutants (single asterisk). In the SPCA1-Q747A transfected culture, GPP130 was clearly detected in untransfected cells (double asterisk). (Scale bar, 10 μm.) (B) Quantitation of percentage of transfected cells without detectable GPP130 (mean ± SE; n = 100 cells per experiment from six independent experiments; P < 0.05). (C) HeLa cells were transfected with HA-tagged SPCA1-WT or Q747A and harvested 24 h posttransfection as described previously (15). Immunoblotting was performed to detect GPP130, HA, and tubulin.