The GIRK1-3 proteins were expressed in the developing brain from the day of birth (P0), showing some differences in a region- and subunit-specific manner (Figs 1 and 2). In the cerebellum, the expression of GIRK1 was low in the molecular layer at P5, increased at P10 and then decreased from P15 to adulthood (Fig. 1A and B). In contrast, GIRK1 levels increased steadily in the granule cell layer (Fig. 1A and B). The expression of GIRK2 was highest in the molecular and granule cell layers at P5, and then decreased until adulthood (Fig. 1A and C). In the white matter, the expression for both GIRK1 and GIRK2 was consistently lower than in the molecular and granule cell layers, showing its highest expression at P5, and then decreasing until adulthood (Fig. 1A-C). The expression of GIRK3 increased from its lowest expression at P5 to a peak at P60 (Fig. 2A and B).
