Pore accessibility during C-type inactivation in Shaker K+ channels.
Shaker K+ channels inactivate through two distinct molecular mechanisms: N-type, which involves the N-terminal domain and C-type that appears to involve structural modifications at the external mouth of the channel. We have tested pore accessibility of the Shaker K+ channel during C-type inactivation using Ba2+ as a probe. We determined that external Ba2+ binds to C-type inactivated channels forming an extremely stable complex; i.e. there is Ba2+ trapping by C-type inactivated channels. The structural changes Shaker channels undergo during C-type inactivation create high energy barriers that hinder Ba2+ exit to either the extracellular solution or to the intracellular solution.
Basso
C
C
Departmento of Biología, Facultad de Ciencias, Universidad de Chile, Santiago.
Labarca
P
P
Stefani
E
E
Alvarez
O
O
Latorre
R
R
D001464:Barium / Q000494:pharmacology*; D001692:Biological Transport; D015640:Ion Channel Gating; D008956:Models, Chemical; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D011487:Protein Conformation; D051637:Shaker Superfamily of Potassium Channels
D015221:Potassium Channels; D051637:Shaker Superfamily of Potassium Channels; D001464:Barium