Work

Large conductance voltage- and calcium-dependent K + channel, a distinct member of voltage-dependent ion channels with seven N-terminal transmembrane segments (S0-S6), an extracellular N terminus, and an intracellular (S9-S10) C terminus

Year: 1997

Type: article

Abstract: Large conductance voltage- and Ca2+-dependent K+ (MaxiK) channels show sequence similarities to voltage-gated ion channels. They have a homologous S1-S6 region, but are unique at the N and C termini. At the C terminus, MaxiK channels have four additional hydrophobic regions (S7-S10) of unknown topology. At the N terminus, we have recently proposed a new model where MaxiK channels have an additional transmembrane region (S0) that confers beta subunit regulation. Using transient expression of epitope tagged MaxiK channels, in vitro translation, functional, and "in vivo" reconstitution assays, we now show that MaxiK channels have seven transmembrane segments (S0-S6) at the N terminus and a S1-S6 region that folds in a similar way as in voltage-gated ion channels. Further, our results indicate that hydrophobic segments S9-S10 in the C terminus are cytoplasmic and unequivocally demonstrate that S0 forms an additional transmembrane segment leading to an exoplasmic N terminus.

Source: Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.94.25.14066

Authors: Pratap Meera, Martin Wallner, Min Song, Ligia Toro

Institution: University of California, Los Angeles

Language: English

Topic: Ion channel regulation and function

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: green

Funder: National Heart, Lung, and Blood Institute

Award: MaxiK channel biology