FIGURE 1.

Different glycosidases increase the TRPV5-mediated Ca²⁺ uptake via plasma membrane stabilization of the channel. A, I/V relationships of untreated, klotho- or endoF-treated HEK293 cells expressing TRPV5 are presented. The solid line represents untreated cells, dashed line represents klotho-treated cells (light gray), and the dotted line represents endoF-treated cells (dark gray). B, TRPV5-mediated Na⁺ current in HEK293 cells was measured. Treatment with β-glucuronidase, klotho, sialidase, or endoF all resulted in a significantly increased current (n = 17–42). C, ⁴⁵Ca²⁺ uptake assays of HEK293 cells transfected with TRPV5 or the empty vector (mock). These cells were untreated or treated with glycosidase (β-glucuronidase, klotho, sialidase, or endoF); D, time-chase assay of cells transfected with TRPV5. The membrane proteins were biotinylated at 0 h. After 3 h incubation without glycosidase, the membrane fraction of TRPV5 was decreased. E, time-chase assay of cells transfected with TRPV5^N358Q. All data are presented as mean ± S.E.; n = 3; *_, p < 0.05, statistically significant.