The first transmembrane domain (TM1) of β2-subunit binds to the transmembrane domain S1 of α-subunit in BK potassium channels.
The BK channel is one of the most broadly expressed ion channels in mammals. In many tissues, the BK channel pore-forming α-subunit is associated to an auxiliary β-subunit that modulates the voltage- and Ca(2+)-dependent activation of the channel. Structural components present in β-subunits that are important for the physical association with the α-subunit are yet unknown. Here, we show through co-immunoprecipitation that the intracellular C-terminus, the second transmembrane domain (TM2) and the extracellular loop of the β2-subunit are dispensable for association with the α-subunit pointing transmembrane domain 1 (TM1) as responsible for the interaction. Indeed, the TOXCAT assay for transmembrane protein-protein interactions demonstrated for the first time that TM1 of the β2-subunit physically binds to the transmembrane S1 domain of the α-subunit.
Centro Interdisciplinario de Neurociencia de Valparaiso, Facultad de Ciencias, Universidad de Valparaíso, Valparaiso, Chile.
Francisco J
FJ
Morera
Abderrahmane
A
Alioua
Pallob
P
Kundu
Marcelo
M
Salazar
Carlos
C
Gonzalez
Agustin D
AD
Martinez
Enrico
E
Stefani
Ligia
L
Toro
Ramon
R
Latorre
D000818:Animals; D002118:Calcium / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D000939:Epitopes / Q000737:chemistry; D005091:Exons; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D007700:Kinetics; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000737:chemistry*; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000737:chemistry*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000737:chemistry; D015221:Potassium Channels / Q000737:chemistry; D017434:Protein Structure, Tertiary; D014162:Transfection
D000939:Epitopes; C494841:KCNMA1 protein, human; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D011188:Potassium; D002118:Calcium