Table 1.
Relative abundance of TRIP8b splice variants expressed in mouse brain and effects of six major variants on HCN1 channel expression and gating. Splice form mRNA abundance was assessed by quantitative real-time PCR analysis as a percentage of total TRIP8b mRNA. The indicated range of values describes the variability observed between different mRNA/cDNA preparations. ΔV1/2 values refer to the difference in the midpoint of activation observed between HCN1 channels expressed without or with the indicated TRIP8b splice variant (see Figure 4 and text). TBD, to be determined.
| TRIP8b Isoform | Effect on HCN1 gating (ΔV1/2) | Effect on HCN1 expression | % TRIP8b mRNA |
|---|---|---|---|
| 1a | -13.4 mV | ∼10-fold reduction | ∼25-30% |
| 1a-2 | -9.3 mV | no effect | <10% |
| 1a-2-3-4 | TBD | TBD | <1% |
| 1a-2-4 | -9.7 mV | ∼5-fold increase | <10% |
| 1a-3-4 | TBD | TBD | <5% |
| 1a-4 | -11.6 mV | ∼6-fold increase | ∼30-40% |
| 1b-2 | -10.7 mV | >100-fold reduction | ∼10-15% |
| 1b-2-3-4 | TBD | TBD | <1% |
| 1b-2-4 | -14.7 mV | >50-fold reduction | ∼10-15% |