Da. Fadool et Ib. Levitan, MODULATION OF OLFACTORY-BULB NEURON POTASSIUM CURRENT BY TYROSINE PHOSPHORYLATION, The Journal of neuroscience, 18(16), 1998, pp. 6126-6137
Insulin causes a suppression of whole-cell voltage-dependent outward c
urrent in cultured neurons from the rat olfactory bulb. This suppressi
on is time-dependent; it is mimicked by application of Src tyrosine ki
nase inside the cell via the whole-cell patch electrode or by treatmen
t of the olfactory bulb neurons with the tyrosine phosphatase inhibito
r pervanadate. The C-type inactivation properties of the outward curre
nt in olfactory bulb neurons resemble those of the cloned Kv1.3 potass
ium channel. In addition, at picomolar concentrations at which it is s
pecific for Kv1.3, the scorpion toxin margatoxin blocks most of the ol
factory bulb neuron outward current. Immunocytochemical analysis demon
strates that Kv1.3 is prominent in the cultured olfactory bulb neurons
. To identify specific amino acid residues that might be important for
potassium current modulation, we examined the effects of pervanadate
and insulin on wild-type and mutant Kv1.3 channels expressed in human
embryonic kidney (HEK 293) cells. As shown previously, treatment with
either pervanadate or insulin suppresses Kv1.3 current in these cells.
Mutational analysis demonstrates that at least two distinct tyrosine
residues are required for current suppression by pervanadate. Insulin
treatment stimulates the tyrosine phosphorylation of Kv1.3 in HEK 293
cells, and a different combination of tyrosine residues is required fo
r the current suppression by insulin. The results suggest that complex
patterns of phosphorylation may be involved in the modulation of neur
onal potassium current by receptor and nonreceptor tyrosine kinases.