Journal: The Journal of Neuroscience
Article Title: Molecular and Cellular Diversity of Neuronal G-Protein-Gated Potassium Channels
Figure Lengend Snippet: Subcellular distributions of GIRK subunits in the hippocampus. Electron micrographs show immunolabeling for GIRK1 and GIRK2 in the stratum radiatum of the CA1 area of WT and GIRK KO mice. den, Dendritic shaft; b, bouton; s, dendritic spine. A , B , GIRK1 immunoparticles were observed primarily along the extrasynaptic plasma membrane (arrows) of dendritic spines of CA1 neurons from WT mice, although perisynaptic labeling (crossed arrow) was also frequently observed. GIRK1 labeling was also found associated with ER cisterna of dendritic shafts and with the spine apparatus (double arrowheads) of spines. C , GIRK1 labeling was never detected within the postsynaptic specialization, as demonstrated with postembedding techniques. D , E , GIRK1 immunoparticles at presynaptic sites were localized to the extrasynaptic plasma membrane (arrowheads) and occasionally to the presynaptic membrane specialization of axon terminals establishing putative excitatory synapses on spines, as confirmed in double-labeling experiments with VGluT1. F-H , GIRK2 immunoparticles were found along the extrasynaptic plasma membrane (arrows) of dendritic shafts of CA1 cells from WT mice, mainly associated with dendritic spines. Both perisynaptic ( G , crossed arrows) and synaptic ( H , double arrow) labeling at asymmetrical synapses was detected, the latter confirmed using postembedding techniques ( I ). J , K , GIRK2 immunoparticles were detected at presynaptic sites (arrowheads), mainly in the extra synaptic plasma membrane, and occasionally in the presynaptic membrane specialization of axon terminals establishing putative excitatory synapses on spines, as confirmed using double-labeling experiments with VGluT1. Note also the GIRK2 immunoreactivity associated with ER cisterna of dendritic shafts and the spine apparatus of dendritic spines ( J , double arrowheads). L , Distribution of GIRK1 and GIRK2 on dendritic spines of CA1 neurons. Data are displayed as percentage frequency of particles in 60-nm-wide bins, starting at the edge of the postsynaptic specialization. M-T , Electron micrographs showing GIRK1 immunoreactivity in the stratum radiatum of the CA1 area in sections taken from GIRK2 KO ( M-P ), GIRK3 KO ( Q , R ), GIRK2/GIRK3 KO ( S ), and GIRK1 KO ( T ) mice. Note that GIRK1 immunoreactivity was still observed along the extrasynaptic plasma membrane (arrows) of dendritic spines and shafts of CA1 neurons from GIRK2 KO and GIRK3 KO mice. Immunoparticles for GIRK1 were also observed at perisynaptic (data not shown) positions and at presynaptic sites along the extrasynaptic plasma membrane (arrowheads) of axon terminals establishing putative excitatory synapses on dendritic spines. A higher proportion of immunoparticles for GIRK1 was detected in the ER cisterna of dendritic shafts and the spine apparatus (double arrowhead). Immunoreactivity for GIRK1 was primarily restricted to the ER of CA1 cells in the hippocampus of GIRK2/GIRK3 KO mice and was absent in sections from a GIRK1 KO mouse. Scale bars, 0.2 μm.
Article Snippet: Rabbit anti-GIRK1, anti-GIRK2, and anti-GIRK3 antibodies were obtained from Alomone Labs (Jerusalem, Israel).
Techniques: Immunolabeling, Mouse Assay, Labeling