to pertussis toxin (PTX) sensitive heterotrimeric G proteins that activate GIRK channels4. Whether the activated Gα subunit or Gβγ dimer directly opened GIRK channels was the focus of an animated debate in the 1980s (see Box 1). Now, a preponderance of evidence supports the conclusion that Gβγ dimers released from PTX-sensitive (Gαi/Gαo) G proteins bind directly to GIRK channels causing them to open5-9 (Box 1).
