Animation 1. Neurosteroid Binding
Exposes a Phosphorylation Site (Model A). This animation shows
one model for how neurosteroids may increase Cl– flux through a GABA-A
receptor. Binding of the neurosteroid (ALLO) allows a protein kinase C (PKC)
phosphorylation site to become accessible. Phosphorylation of the channel
increases flux through the channel, allowing more Cl– ions to flow
through the channel in the presence of GABA than when the channel is activated
by GABA without prior phosphorylation. The top of this animated gif shows how
the channel, the ligands, and G protein-activated PKC may be interacting at the
plasma membrane. The bottom of the animation shows how these interactions affect
the current trace recorded using electrophysiological techniques. In the current
trace, the size of the signal is smaller in the absence of neurosteroid compared
to the size of the signal after exposure to neurosteroid and subsequent
phosphorylation of the channel.