AtKC1, a conditionally targeted Shaker-type subunit, regulates the activity of plant K+channels
Articolo
Data di Pubblicazione:
2008
Citazione:
AtKC1, a conditionally targeted Shaker-type subunit, regulates the activity of plant K+channels / G. Duby, E. Hosy, C. Fizames, C. Alcon, A. Costa, H.´ Sentenac, J.B. Thibaud. - In: PLANT JOURNAL. - ISSN 0960-7412. - 53:1(2008 Jan), pp. 115-123. [10.1111/j.1365-313X.2007.03324.x]
Abstract:
Amongst the nine voltage-gated K+ channel (Kv) subunits expressed in Arabidopsis, AtKC1 does not seem to
form functional Kv channels on its own, and is therefore said to be silent. It has been proposed to be a
regulatory subunit, and to significantly influence the functional properties of heteromeric channels in which it
participates, along with other Kv channel subunits. The mechanisms underlying these properties of AtKC1
remain unknown. Here, the transient (co-)expression of AtKC1, AKT1 and/or KAT1 genes was obtained in
tobacco mesophyll protoplasts, which lack endogenous inward Kv channel activity. Our experimental
conditions allowed both localization of expressed polypeptides (GFP-tagging) and recording of heterologously
expressed Kv channel activity (untagged polypeptides). It is shown that AtKC1 remains in the endoplasmic
reticulum unless it is co-expressed with AKT1. In these conditions heteromeric AtKC1-AKT1 channels are
obtained, and display functional properties different from those of homomeric AKT1 channels in the same
context. In particular, the activation threshold voltage of the former channels is more negative than that of the
latter ones. Also, it is proposed that AtKC1-AKT1 heterodimers are preferred to AKT1-AKT1 homodimers
during the process of tetramer assembly. Similar results are obtained upon co-expression of AtKC1 with KAT1.
The whole set of data provides evidence that AtKC1 is a conditionally-targeted Kv subunit, which probably
downregulates the physiological activity of other Kv channel subunits in Arabidopsis.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Arabidopsis; AtKC1; GFP; Heteromerization; Potassium; Silent channel subunit
Elenco autori:
G. Duby, E. Hosy, C. Fizames, C. Alcon, A. Costa, H.´ Sentenac, J.B. Thibaud
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