Y1795C (LQT-3)
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| Current Density | Shift in V1/2 of activation | Shift in V1/2 of inactivation | Kinetic of Inactivation | Recovery from Inactivation | I-sus | Expression System | Other | Reference |
|---|---|---|---|---|---|---|---|---|
| WT: -370±32pA/pF |
WT: -23.3±1mV |
WT: -62.8±0.8 mV . |
4-fold increase | HEK293 with beta1 |
At 32ºC greater development of slow inactivation. | Rivolta et al. 2001 | ||
| YC: -448±42pA/pF |
YC: -24.3±1.4mV |
YC: -65.6±0.4 mV |
Time course of YC channel speeds with frequency | |||||
| YC, slightly higher than WT | N.S. | N.S | Slower | Slower |
N.S. : non different from WT
COMMENTS ON IN VITRO
DATA
Y1795C channels inactivate more slowly than WT channels and are characterized
by a prominent fraction of current that is maintained during prolonged depolarization.
Both of these changes in channel properties are expected to contribute with
more inward current during both early and late phases of the action potential
and hence are consistent with prolongation of the cellular action potential
and with the Long QT syndrome phenotype observed in the gene carriers. This
mutation has been associated with a malignant form of LQTS and a histidine substitution
at the same codon (Y1795H) has been found in a family
with Brugada syndrome phenotype and the 1795InsD
mutation has been found in a family with overlapping BS/LQTS phenotype..