RGD Reference Report - The molecular basis for the actions of KVbeta1.2 on the opening and closing of the KV1.2 delayed rectifier channel. - Rat Genome Database

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The molecular basis for the actions of KVbeta1.2 on the opening and closing of the KV1.2 delayed rectifier channel.

Authors: Peters, CJ  Vaid, M  Horne, AJ  Fedida, D  Accili, EA 
Citation: Peters CJ, etal., Channels (Austin). 2009 Sep-Oct;3(5):314-22. Epub 2009 Sep 16.
RGD ID: 10047171
Pubmed: PMID:19713757   (View Abstract at PubMed)

Cytosolic K(V)beta1 subunits co-assemble with transmembrane K(V)1 channel alpha-subunits and have complex effects on channel function. Fast inactivation, the most obvious effect conferred, is due to fast open channel block resulting from the binding of the N-terminus within the inner mouth of the pore. K(V)beta1 subunits also slow current deactivation, enhance slow inactivation and shift channel activation to more negative voltages, but the mechanisms underlying these actions are not known. Here we use voltage clamp fluorimetry at sites near the extracellular end of the S4 helix, the channel's primary voltage sensor, in combination with voltage clamp electrophysiology, to independently track the movement of the S4 helix along with ionic current, and thus identify the structural and mechanistic means by which the K(V)beta1.2 subunit confers its actions on the K(V)1.2 channel. We show that the negative shift in current activation is not due to direct actions of K(V)beta1.2 on the S4 segment. Instead, this shift results from an apparent saturation of channel activation at depolarized potentials as the extent of open channel block by the K(V)beta1.2 N-terminus progressively increases. The return of fluorescence to baseline is slowed along with current deactivation. According to our data, this is due to an inability of the activation gate to close while the K(V)beta1.2 N-terminus occupies the pore and strong coupling of the gate with the S4 segment. Together with data from previous studies, our findings provide a complete and coherent picture of the functional and structural interactions between K(V)beta1.2 and K(V)1.2.

Gene Ontology Annotations    Click to see Annotation Detail View

Molecular Function
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
delayed rectifier potassium channel activity enablesIMP 10047171PMID:19713757UniProt 

Objects Annotated

Genes (Rattus norvegicus)
Kcna2  (potassium voltage-gated channel subfamily A member 2)


Additional Information