Structure of the human two-pore domain potassium ion channel TRAAK
Rod MacKinnon group (The Rockefeller University)
Rod MacKinnon's group at the Rockefeller University solved
the structure of the human two-pore domain potassium ion channel TRAAK.
Potassium-selective ion channels called TRAAK are expressed predominantly in
the brain and nervous system where they control cellular electrical
excitability. These channels are exquisitely sensitive to the chemical and
mechanical properties of the cellular membrane in which they reside. They
are activated by polyunsaturated fatty acids including arachidonic acid and
by mechanical force. The 3.8-Å crystal structure of the human TRAAK
channel is the first of a two-pore domain potassium ion channel. It reveals
an unprecedented helical cap structure on the extracellular side of the
membrane that prevents certain toxins from venomous animals from blocking its
membrane environment. The structure provides a framework for future studies
probing the mechanistic basis for modulation of channel activity by chemical
and mechanical stimuli.
Figure: Ribbon representation of the
TRAAK K+ ion channel viewed from the membrane plane with the
extracellular milieu above. The subunits of the dimeric channel are colored
blue, and gray, and K+ ions are green spheres.
Brohawn, SG, del Marmol, J, MacKinnon, R. Crystal structure of the human K2P
TRAAK, a lipid- and mechano-sensitive K+ ion channel, Science 335, 436-441