Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2001-9-12
pubmed:abstractText
Plants have multiple potassium (K(+)) uptake and efflux mechanisms that are expressed throughout plant tissues to fulfill different physiological functions. Several different classes of K(+) channels and carriers have been identified at the molecular level in plants. K(+) transporters of the HKT1 superfamily have been cloned from wheat (Triticum aestivum), Arabidopsis, and Eucalyptus camaldulensis. The functional characteristics as well as the primary structure of these transporters are diverse with orthologues found in bacterial and fungal genomes. In this report, we provide a detailed characterization of the functional characteristics, as expressed in Xenopus laevis oocytes, of two cDNAs isolated from E. camaldulensis that encode proteins belonging to the HKT1 superfamily of K(+)/Na(+) transporters. The transport of K(+) in EcHKT-expressing oocytes is enhanced by Na(+), but K(+) was also transported in the absence of Na(+). Na(+) is transported in the absence of K(+) as has been demonstrated for HKT1 and AtHKT1. Overall, the E. camaldulensis transporters show some similarities and differences in ionic selectivity to HKT1 and AtHKT1. One striking difference between HKT1 and EcHKT is the sensitivity to changes in the external osmolarity of the solution. Hypotonic solutions increased EcHKT induced currents in oocytes by 100% as compared with no increased current in HKT1 expressing or uninjected oocytes. These osmotically sensitive currents were not enhanced by voltage and may mediate water flux. The physiological function of these osmotically induced increases in currents may be related to the ecological niches that E. camaldulensis inhabits, which are periodically flooded. Therefore, the osmosensing function of EcHKT may provide this species with a competitive advantage in maintaining K(+) homeostasis under certain conditions.
pubmed:commentsCorrections
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pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0032-0889
pubmed:author
pubmed:issnType
Print
pubmed:volume
127
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
283-94
pubmed:dateRevised
2010-9-14
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Characterization of two HKT1 homologues from Eucalyptus camaldulensis that display intrinsic osmosensing capability.
pubmed:affiliation
CSIRO Plant Industry Horticulture Unit, G.P.O. Box 350, Glen Osmond, South Australia 5064, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't