Energy landscape of the reactions governing the Na+ deeply occluded state of the Na+/K+-ATPase in the giant axon of the Humboldt squid.

ABSTRACT: The Na(+)/K(+) pump is a nearly ubiquitous membrane protein in animal cells that uses the free energy of ATP hydrolysis to alternatively export 3Na(+) from the cell and import 2K(+) per cycle. This exchange of ions produces a steady-state outwardly directed current, which is proportional in magnitude to the turnover rate. Under certain ionic conditions, a sudden voltage jump generates temporally distinct transient currents mediated by the Na(+)/K(+) pump that represent the kinetics of extracellular Na(+) binding/release and Na(+) occlusion/deocclusion transitions. For many years, these events have escaped a proper thermodynamic treatment due to the relatively small electrical signal. Here, taking the advantages offered by the large diameter of the axons from the squid Dosidicus gigas, we h

SUBMITTER: Castillo JP 

PROVIDER: S-EPMC3251152 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature