Abstract
ABSTRACTDuring the recording of whole cell currents from stably transfected HEK-293 cells, the decline of currents carried by the recombinant human Cav2.3+β3 channel subunits is related to adenosine triphosphate (ATP) depletion after rupture of the cells. It reduces the number of functional channels and leads to a progressive shift of voltage-dependent gating to more negative potentials (Neumaier F., et al., 2018). Both effects can be counteracted by hydrolysable ATP, whose protective action is almost completely prevented by inhibition of serine/threonine but not tyrosine or lipid kinases. These findings indicate that ATP promotes phosphorylation of either the channel or an associated protein, whereas dephosphorylation during cell dialysis results in run-down. Protein phosphorylation is required for Cav2.3 channel function and could directly influence the normal features of current carried by these channels. Therefore, results from in vitro and in vivo phosphorylation of Cav2.3 are summarized to come closer to a functional analysis of structural variations in Cav2.3 splice variants.
Highlights
Covalent modification of ion channels and other proteins is a common event during cellular growth, metabolic regulation and neuronal signalling
During the recording of whole cell currents from stably transfected HEK-293 cells, the decline of currents carried by the recombinant human Cav2.3+β3 channel subunits is related to adenosine triphosphate (ATP) depletion after rupture of the cells
It reduces the number of functional channels and leads to a progressive shift of voltage-dependent gating to more negative potentials (Neumaier F., et al, 2018)
Summary
Covalent modification of ion channels and other proteins is a common event during cellular growth, metabolic regulation and neuronal signalling. Members of the second calcium channel subfamily (Cav2) are mainly expressed in the neuronal system [6] and were early analyzed as in vitro phosphorylation targets of protein kinase A [7]. In HEK-293 cells expressing members of the Cav2 subfamily, the mechanism of Ca2+ channel modulation by opioid receptor (OR) activation was analyzed and the different types of ORs were cotransfected with Cav2.3.
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