Dual palmitoylation of PSD-95 mediates its vesiculotubular sorting, postsynaptic targeting, and ion channel clustering.
Postsynaptic density-95 (PSD-95/SAP-90) is a palmitoylated peripheral membrane protein that scaffolds ion channels at excitatory synapses. To elucidate mechanisms for postsynaptic ion channel clustering, we analyzed the cellular trafficking of PSD-95. We find that PSD-95 transiently associates with a perinuclear membranous compartment and traffics with vesiculotubular structures, which migrate in a microtubule-dependent manner. Trafficking of PSD-95 with these vesiculotubular structures requires dual palmitoylation, which is specified by five consecutive hydrophobic residues at the NH(2) terminus. Mutations that disrupt dual palmitoylation of PSD-95 block both ion channel clustering by PSD-95 and its synaptic targeting. Replacing the palmitoylated NH(2) terminus of PSD-95 with alternative palmitoylation motifs at either the NH(2) or COOH termini restores ion channel clustering also induces postsynaptic targeting, respectively. In brain, we find that PSD-95 occurs not only at PSDs but also in association with intracellular smooth tubular structures in dendrites and spines. These data imply that PSD-95 is an itinerant vesicular protein; initial targeting of PSD-95 to an intracellular membrane compartment may participate in postsynaptic ion channel clustering by PSD-95.
El-Husseini
A E
AE
Department of Physiology, University of California at San Francisco, San Francisco, California 94143, USA.
Craven
S E
SE
Chetkovich
D M
DM
Firestein
B L
BL
Schnell
E
E
Aoki
C
C
Bredt
D S
DS
D000818:Animals; D001692:Biological Transport; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D016764:Cell Polarity; D002540:Cerebral Cortex / Q000166:cytology; D016384:Consensus Sequence; D000076122:Disks Large Homolog 4 Protein; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism; D049452:Green Fluorescent Proteins; D051528:Guanylate Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051665:Kv1.4 Potassium Channel; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D009703:Nucleoside-Phosphate Kinase / Q000378:metabolism; D010169:Palmitic Acids / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000074407:SAP90-PSD95 Associated Proteins; D013569:Synapses
D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; C496977:KCNA4 protein, human; C496979:Kcna4 protein, rat; D051665:Kv1.4 Potassium Channel; D008164:Luminescent Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010169:Palmitic Acids; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011993:Recombinant Fusion Proteins; D000074407:SAP90-PSD95 Associated Proteins; C033652:postsynaptic density proteins; D049452:Green Fluorescent Proteins; D020126:Brefeldin A; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases; D015739:Nocodazole