Figure 4. AKAP15 and AKAP79ΔPIX regulate CaV1.2 channels through a modified leucine zipper motif located in the DCT. (A) Representative IBa through CaV1.2Δ1800 and CaV1.2Δ1800 + DCT channels coexpressed with cDNA ratios of 0.003:1 WT AKAP15 or AKAP15LZM in the absence or presence of 5 µM forskolin (Fsk) elicited by a test pulse to 10 mV from a holding potential of −80 mV. (B) Mean current-voltage relationships for CaV1.2Δ1800 and CaV1.2Δ1800 + DCT channels coexpressed with cDNA ratios of 0.003:1 WT AKAP15 or AKAP15LZM and 5 µM forskolin. (C) Coupling ratio (nA/pC) for CaV1.2Δ1800 and CaV1.2Δ1800 + DCT channels with WT AKAP15 or AKAP15LZM, without and with 5 µM forskolin. Dashed black line indicates mean coupling ratio for unstimulated CaV1.2Δ1800 + DCT with AKAP15LZM. **, P < 0.01 versus control. (D) Representative IBa through CaV1.2Δ1800 channels coexpressed with WT DCT or DCTLZM and a cDNA ratio of 0.003:1 WT AKAP15 in the absence or presence of 5 µM forskolin. (E) Mean current-voltage relationships for CaV1.2Δ1800 channels coexpressed with either WT DCT or DCTLZM and a cDNA ratio of 0.003:1 WT AKAP15 without or with 5 µM forskolin. (F) Coupling efficiency (nA/pC) for CaV1.2Δ1800 channels in E. Dashed line indicates mean coupling ratio for unstimulated CaV1.2Δ1800 + DCTLZM with AKAP15. **, P < 0.01 versus control. (G) Representative IBa through CaV1.2Δ1800 channels coexpressed with WT DCT or DCTLZM and 0.01:1 AKAP79ΔPIX in the absence or presence of 5 µM forskolin. (H) Mean current-voltage relationships for CaV1.2Δ1800 channels with either WT DCT or DCTLZM, a cDNA ratio of 0.01:1 AKAP79ΔPIX, and 5 µM forskolin. (B, C, E, F, and H) Error bars are SEM. (I) Coupling ratio (nA/pC) for CaV1.2Δ1800 channels in H. Dashed line indicates mean coupling ratio for unstimulated CaV1.2Δ1800 + DCTLZM with AKAP79ΔPIX. n values and means ± SEM are indicated. **, P < 0.01 versus control. Significance was determined by ANOVA.
Figure 4.

AKAP15 and AKAP79ΔPIX regulate CaV1.2 channels through a modified leucine zipper motif located in the DCT. (A) Representative IBa through CaV1.2Δ1800 and CaV1.2Δ1800 + DCT channels coexpressed with cDNA ratios of 0.003:1 WT AKAP15 or AKAP15LZM in the absence or presence of 5 µM forskolin (Fsk) elicited by a test pulse to 10 mV from a holding potential of −80 mV. (B) Mean current-voltage relationships for CaV1.2Δ1800 and CaV1.2Δ1800 + DCT channels coexpressed with cDNA ratios of 0.003:1 WT AKAP15 or AKAP15LZM and 5 µM forskolin. (C) Coupling ratio (nA/pC) for CaV1.2Δ1800 and CaV1.2Δ1800 + DCT channels with WT AKAP15 or AKAP15LZM, without and with 5 µM forskolin. Dashed black line indicates mean coupling ratio for unstimulated CaV1.2Δ1800 + DCT with AKAP15LZM. **, P < 0.01 versus control. (D) Representative IBa through CaV1.2Δ1800 channels coexpressed with WT DCT or DCTLZM and a cDNA ratio of 0.003:1 WT AKAP15 in the absence or presence of 5 µM forskolin. (E) Mean current-voltage relationships for CaV1.2Δ1800 channels coexpressed with either WT DCT or DCTLZM and a cDNA ratio of 0.003:1 WT AKAP15 without or with 5 µM forskolin. (F) Coupling efficiency (nA/pC) for CaV1.2Δ1800 channels in E. Dashed line indicates mean coupling ratio for unstimulated CaV1.2Δ1800 + DCTLZM with AKAP15. **, P < 0.01 versus control. (G) Representative IBa through CaV1.2Δ1800 channels coexpressed with WT DCT or DCTLZM and 0.01:1 AKAP79ΔPIX in the absence or presence of 5 µM forskolin. (H) Mean current-voltage relationships for CaV1.2Δ1800 channels with either WT DCT or DCTLZM, a cDNA ratio of 0.01:1 AKAP79ΔPIX, and 5 µM forskolin. (B, C, E, F, and H) Error bars are SEM. (I) Coupling ratio (nA/pC) for CaV1.2Δ1800 channels in H. Dashed line indicates mean coupling ratio for unstimulated CaV1.2Δ1800 + DCTLZM with AKAP79ΔPIX. n values and means ± SEM are indicated. **, P < 0.01 versus control. Significance was determined by ANOVA.

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