Lack of Tyrosine Protein Kinase Regulation of L-Type Ca²⁺ Channel Current in Transfected Cells Stably Expressing α_1C-b Subunit

Abstract

Tyrosine protein kinase (Tyr-PK) regulation of L-type Ca²⁺ channel (Ca_L) current was studied in COS-7 cells expressing vascular smooth muscle-type α_1C-b with no auxiliary subunit by using a whole-cell voltage clamp. The averaged peak amplitude of Ca_L currents was −0.33 ± 0.03 at holding potential of −60 mV. Na₃VO₄, genistein and phosphorylated p60^c-src peptide had no effect on the current. Thus the α_1C-b subunit may not be involved in Tyr-PK regulation of Ca_L current.