Fig. 3.

Rem and Rad prevent de novo expression of Ca_V1.2 ionic current but not T type Ca²⁺ currents. (A) Representative Ba²⁺ current elicited by a voltage step from –80 to 10 mV in HEK293 cells transiently transfected with expression vectors encoding Ca_V1.2, β_2a, and GFP. (Bars = 10 pA/pF and 50 ms.) (B) HEK293 cells cotransfected with Ca_V1.2, β_2a, and GFP-tagged wild-type Rem or Rad (same conditions as A). No current is detectable. (C) Current–voltage relationships for cells transfected with Ca_V1.2, β_2a, and unfused GFP (filled squares) or Ca_V1.2, β_2a, and GFP-Rem (filled circles) or Rad (open triangles). Average and SE from six to eight experiments for each group are shown. (D and E) Representative control Ca_V3.2 ionic current and Ca_V3.2 ionic current coexpressed with GFP-Rem. Also, coexpression of β_2a with Ca_V3.1 or 3.2 or coexpression of Ca_Vβ_2a, GFP-Rem, and Ca_V3.1 or 3.2 had no effect on T type Ca²⁺ channel current expression (data not shown for Ca_V3.1). (F and G) Coexpression of Ca_V3.2, Ca_V1.2, β2a display a complex kinetic pattern that resolves to an ionic current that on Rem expression is indistinguishable from the Ca_V3.2 expressed alone. (H) The current–voltage curve shows that Ca_V3.2 current amplitude expression is not altered by Rem coexpression. Average and SE from six to eight experiments for each group are shown.