Why the study?
Does the alpha k subunit of Gk stimulate potassium channel activity in mammalian atrial myocytes?
Does the alpha k subunit of Gk stimulate potassium channel activity in mammalian atrial myocytes?
The study demonstrates that the alpha subunit of the Gk protein is responsible for opening atrial potassium channels, establishing its mechanism of action.
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αk mediates atrial K+ channel activation in mammalian patches; leaves open human in vivo relevance and therapeutic translation.
Guanine nucleotide binding (G) proteins (subunit composition alpha beta gamma) dissociate on activation with guanosine triphosphate (GTP) analogs and magnesium to give alpha-guanine nucleotide complexes and free beta gamma subunits. Whether the opening of potassium channels by the recently described Gk in isolated membrane patches from mammalian atrial myocytes was mediated by the alpha k subunit or beta gamma dimer was tested. The alpha k subunit was found to be active, while the beta gamma dimer was inactive in stimulating potassium channel activity. Thus, Gk resembles Gs, the stimulatory regulatory component of adenylyl cyclase, and transducin, the regulatory component of the visual system, in that it regulates its effector function--the activity of the ligand-gated potassium channel--through its guanine nucleotide binding subunit.
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Codina et al. (1987) studied this question.
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