The Plant cell, 2005-05, Vol.17 (5), p.1532-1548
2005
Volltextzugriff (PDF)
Details
- Autor(en) / Beteiligte
- Titel
- Regulation by External K⁺ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range
- Ist Teil von
- The Plant cell, 2005-05, Vol.17 (5), p.1532-1548
- Ort / Verlag
- United States: American Society of Plant Biologists
- Erscheinungsjahr
- 2005
- Quelle
- MEDLINE
- Beschreibungen/Notizen
- An inward Shaker K⁺ channel identified in Zea mays (maize), ZmK2.1, displays strong regulation by external K⁺ when expressed in Xenopus laevis (African clawed frog) oocytes or COS cells. ZmK2.1 is specifically activated by K⁺ with an apparent K[subscript m] close to 15 mM independent of the membrane hyperpolarization level. In the absence of K⁺, ZmK2.1 appears to enter a nonconducting state. Thus, whatever the membrane potential, this maize channel cannot mediate K⁺ influx in the submillimolar concentration range, unlike its relatives in Arabidopsis thaliana. Its expression is restricted to the shoots, the strongest signal (RT-PCR) being associated with vascular/bundle sheath strands. Based on sequence and gene structure, the closest relatives of ZmK2.1 in Arabidopsis are K⁺ Arabidopsis Transporter 1 (KAT1) (expressed in guard cells) and KAT2 (expressed in guard cells and leaf phloem). Patch-clamp analyses of guard cell protoplasts reveal a higher functional diversity of K⁺ channels in maize than in Arabidopsis. Channels endowed with regulation by external K⁺ similar to that of ZmK2.1 (channel activity regulated by external K⁺ with a K[subscript m] close to 15 mM, regulation independent of external Ca²⁺) constitute a major component of the maize guard cell inward K⁺ channel population. The presence of such channels in maize might reflect physiological traits of C4 and/or monocotyledonous plants.
- Sprache
- Englisch
- Identifikatoren
- ISSN: 1040-4651eISSN: 1532-298XDOI: 10.1105/tpc.104.030551Titel-ID: cdi_pubmedcentral_primary_oai_pubmedcentral_nih_gov_1091772
- Format
- –
- Schlagworte
- Amino Acid Sequence, Arabidopsis Proteins - metabolism, Base Sequence, Cation Transport Proteins - metabolism, cell lines, Cell Membrane - metabolism, Complementary DNA, Corn, COS cells, electric current, Electric potential, electrophysiology, Extracellular Fluid - metabolism, gene expression, Gene expression regulation, genes, Guard cells, Introns, ion transport, Life Sciences, Membrane Potentials - physiology, messenger RNA, Molecular Sequence Data, nucleotide sequences, Oocytes, Patch-Clamp Techniques, Plant cells, Plant Leaves - metabolism, Plant Proteins - genetics, Plant Proteins - isolation & purification, Plant Proteins - metabolism, Plants, potassium, Potassium - metabolism, potassium channels, Potassium Channels - genetics, Potassium Channels - isolation & purification, Potassium Channels - metabolism, Protoplasts - metabolism, Species Specificity, Vegetal Biology, Xenopus laevis, Zea mays, Zea mays - genetics, Zea mays - metabolism