Molecular determinants for subcellular localization of PSD-95 with an interacting K+ channel.
Ion channels and PSD-95 are colocalized in specific neuronal subcellular locations by an unknown mechanism. To investigate mechanisms of localization, we used biolistic techniques to express GFP-tagged PSD-95 (PSD-95:GFP) and the K(+)-selective channel Kv1.4 in slices of rat cortex. In pyramidal cells, PSD-95:GFP required a single PDZ domain and a region including the SH3 domain for localization to postsynaptic sites. When transfected alone, PSD-95:GFP was present in dendrites but absent from axons. When cotransfected with Kv1.4, PSD-95:GFP appeared in both axons and dendrites, while Kv1.4 was restricted to axons. When domains that mediate the interaction of Kv1.4 and PSD-95 were disrupted, Kv1.4 localized nonspecifically. Our results provide evidence that Kv1.4 itself may determine its subcellular location, while an associated MAGUK protein is a necessary but not sufficient cofactor.
Howard Hughes Medical Institute and Children's Hospital, Boston, Massachusetts 02115, USA.
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Arnold
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Clapham
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D049452:Green Fluorescent Proteins; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D047908:Intracellular Signaling Peptides and Proteins; D051665:Kv1.4 Potassium Channel; D008164:Luminescent Proteins / Q000235:genetics; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D017966:Pyramidal Cells / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution / Q000502:physiology
D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D007202:Indicators and Reagents; D047908:Intracellular Signaling Peptides and Proteins; C496979:Kcna4 protein, rat; D051665:Kv1.4 Potassium Channel; D008164:Luminescent Proteins; D008565:Membrane Proteins; C501451:Mpp2 protein, rat; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011993:Recombinant Fusion Proteins; C033652:postsynaptic density proteins; D049452:Green Fluorescent Proteins