An extracellular cation coordination site influences ion conduction of OsHKT2;2

BMC Plant Biology

Table 1 Electrophysiological characterisation of OsHKT2;2 and its mutants. The presence of three current characteristics are specified according to their degree of occurrence: very strong (+++), medium (++) or weak (+)

	Functionality	Currents enhance at rising Na⁺ concentration (Na03K0 vs. Na30K0)	Current increase with 1 mM K⁺	Lack of current enhancement at rising K⁺ concentration (Na30K0 vs. Na30K30)
wt		+++	+++	+++
P71A	like wt	+++	+++	+++
D75A	comparable to wt	++	+++	+++
D75N	comparable to wt	+++	+++	++
D501A	comparable to wt	++	+++	+++
D501N	comparable to wt	++	+++	++
K504R	altered kinetics	+	+++	+
K504Q	altered kinetics	+	+++	+
K504A	no conduction^a
K504E	no conduction

^aIn some oocytes, very small currents could be detected 2–3 days after RNA injection. This mutant might function in a very inefficient manner so that currents accumulate to a measurable current only after long expression times. After two days of expression though, no currents comparable to wt or other mutants could be measured

ISSN: 1471-2229