Expression of GIRK proteins in cultured rat E18 hippocampal neurons. (a) Overexpression of GIRK1 and GIRK2 proteins in cells coinfected with AdGIRK1+2. Total cellular protein was loaded (50 μg per lane): adult hippocampus (lane 1); 4 d-cultured neurons (lane 2); 4 d-cultured AdGIRK1+2-coinfected neurons, 3 d postinfection (lane 3). Left and right blots were probed with affinity-purified anti-GIRK1 and -GIRK2 antibodies, respectively. Protein samples were separated by SDS/PAGE with prestained molecular weight markers (Amersham) in neighboring lanes. The molecular weights of the marker proteins are indicated on the left with dotted lines across the gels. (b) Time-dependent expression of GIRK1 (Upper) and GIRK2 protein (Lower) in vitro. Total cellular protein of E18 neurons cultured for 4, 14, and 21 d, and of adult hippocampus was used (100 μg per lane) and probed with affinity-purified anti-GIRK1 and -GIRK2 antibodies, respectively.