Fig. 1

Functional and biochemical analysis of glycosylation-deficient Ca_v3.2 channels. a Schematic representation of the membrane topology of Ca_v3.2 channel depicting the localization of asparagine residues within potential non-canonical glycosylation motifs. b Result of the in-silico N-glycosylation prediction. Position of the key asparagine residues (N) within the potential glycosylation motif (NXC) is indicated, along with the quantitative (threshold 0.5) and qualitative score. Pro-X1 indicates the presence of a proline residue in position + 1 of the asparagine residue which is known to limit the likelihood for glycosylation. c Representative T-type current traces recorded from tsA-201 cells expressing wild-type (WT) Ca_v3.2 channels (black traces), and N258Q (blue traces), N335Q (green traces), N345Q (purple traces), N1780Q (orange traces) mutated channels in response to 150 ms depolarizing steps to values ranging from − 90 to + 30 mV from a holding potential of − 100 mV. d Corresponding mean peak current density–voltage (I/V) relationship. The I/V curve of the WT channel is reported in dotted line for comparison. e Corresponding mean normalized maximal macroscopic conductance (G_max) values obtained from the fit of the I/V curves with a modified Boltzmann equation. f Representative immunoblot of Ca_v3.2 channel variants from total cell lysate (total expression, left panel) and corresponding mean total expression as percent of WT channels. The expression of the channels was normalized to Na⁺/K⁺ ATPase. g Legend same as in (f) but for surface biotinylated fractions (surface expression). The biochemical analysis was repeated five times from independent transfections with similar results