Figure 6. The role of c-Src proteins in... | Rockefeller University Press

Figure 6.

$Figure 6. The role of c-Src proteins in GABABR-mediated inhibition by c-Vc1.1 in HEK cells stably expressing human Cav2.3c channels and GABABRs. (A) Time course of IBa through Cav2.3c channels in the absence (control) and presence of 200 nM c-Vc1.1 or 50 µM baclofen. Bars indicate c-Vc1.1 or baclofen application. Overexpression of wild-type c-Src protein increases the IBa fraction inhibited by c-Vc1.1 (top). Overexpression of the double mutant c-Src (K295R/Y527F) (middle) or pretreatment with the phosphorylated pp60c-Src peptide (50 µM) (bottom) abolishes the effect of c-Vc1.1 and reduces baclofen inhibition of IBa, respectively. Representative current traces (right) are shown at the times indicated by lowercase letters (see Fig.1 B for control). IBa was evoked by 150 ms, 0.1-Hz depolarizations to 10 mV, from an HP of −80 mV (voltage inset). Peak current amplitudes were plotted as a function of time. Horizontal dotted lines indicate zero-current levels. (B) Average data (±SEM) of IBa inhibition by c-Vc1.1 or baclofen after pp60c-Src peptide (50 µM) pretreatment or wild-type c-Src coexpression in Cav2.1/GABABR or Cav2.3/GABABR cells, respectively, or double mutant c-Src (K295R/Y527F) coexpression in Cav2.3/GABABR cells (*, P < 0.001 vs. controls; one-way ANOVA). The number of experiments is in parentheses.$

The role of c-Src proteins in GABA_BR-mediated inhibition by c-Vc1.1 in HEK cells stably expressing human Ca_v2.3c channels and GABA_BRs. (A) Time course of I_Ba through Ca_v2.3c channels in the absence (control) and presence of 200 nM c-Vc1.1 or 50 µM baclofen. Bars indicate c-Vc1.1 or baclofen application. Overexpression of wild-type c-Src protein increases the I_Ba fraction inhibited by c-Vc1.1 (top). Overexpression of the double mutant c-Src (K295R/Y527F) (middle) or pretreatment with the phosphorylated pp60c-Src peptide (50 µM) (bottom) abolishes the effect of c-Vc1.1 and reduces baclofen inhibition of I_Ba, respectively. Representative current traces (right) are shown at the times indicated by lowercase letters (see Fig.1 B for control). I_Ba was evoked by 150 ms, 0.1-Hz depolarizations to 10 mV, from an HP of −80 mV (voltage inset). Peak current amplitudes were plotted as a function of time. Horizontal dotted lines indicate zero-current levels. (B) Average data (±SEM) of I_Ba inhibition by c-Vc1.1 or baclofen after pp60c-Src peptide (50 µM) pretreatment or wild-type c-Src coexpression in Ca_v2.1/GABA_BR or Ca_v2.3/GABA_BR cells, respectively, or double mutant c-Src (K295R/Y527F) coexpression in Ca_v2.3/GABA_BR cells (*, P < 0.001 vs. controls; one-way ANOVA). The number of experiments is in parentheses.