ISSN:
1573-5036
Keywords:
cDNA
;
cloning
;
heterologous expression
;
high-affinity K+ transport
;
K+ channel
;
K+ transport
;
oocyte
;
root
;
yeast
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Recently, two K+-transport cDNAs, KAT1 and AKT1, were cloned in Arabidopsis thaliana. These cDNAs had structural similarities to K+ channel genes in animals, and also conferred the ability for growth on micromolar levels of K+ when expressed in K+ transport-defective yeast mutants. In this study, we examined the possibility that KAT1 encodes the high-affinity K+ transport system that has been previously characterized in plant roots, by studying the concentration-dependent kinetics of K+ transport for KAT1 expressed in Xenopus oocytes and Saccharomyces cerevisiae. In both organisms, the K+ transport system encoded by KAT1 yielded Michaelis-Menten kinetics with a high Km for K+ (35 mM in oocytes, 0.6 mM in yeast cells). Furthermore, Northern analysis indicated that KAT1 is expressed primarily in the Arabidopsis shoot. These results strongly suggest that the system encoded by KAT1 is not a root high-affinity K+ transporter.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00024997
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