Differential palmitoylation directs the AMPA receptor-binding protein ABP to spines or to intracellular clusters.
Long-term changes in excitatory synapse strength are thought to reflect changes in synaptic abundance of AMPA receptors mediated by receptor trafficking. AMPA receptor-binding protein (ABP) and glutamate receptor-interacting protein (GRIP) are two similar PDZ (postsynaptic density 95/Discs large/zona occludens 1) proteins that interact with glutamate receptors 2 and 3 (GluR2 and GluR3) subunits. Both proteins have proposed roles during long-term potentiation and long-term depression in the delivery and anchorage of AMPA receptors at synapses. Here we report a variant of ABP-L (seven PDZ form of ABP) called pABP-L that is palmitoylated at a cysteine residue at position 11 within a novel 18 amino acid N-terminal leader sequence encoded through differential splicing. In cultured hippocampal neurons, nonpalmitoylated ABP-L localizes with internal GluR2 pools expressed from a Sindbis virus vector, whereas pABP-L is membrane targeted and associates with surface-localized GluR2 receptors at the plasma membrane in spines. Mutation of Cys-11 to alanine blocks the palmitoylation of pABP-L and targets the protein to intracellular clusters, confirming that targeting the protein to spines is dependent on palmitoylation. Non-palmitoylated GRIP is primarily intracellular, but a chimera with the pABP-L N-terminal palmitoylation sequence linked to the body of the GRIP protein is targeted to spines. We suggest that pABP-L and ABP-L provide, respectively, synaptic and intracellular sites for the anchorage of AMPA receptors during receptor trafficking to and from the synapse.
DeSouza
Sunita
S
Howard Hughes Medical Institute, Department of Biochemistry, New York University School of Medicine, New York, New York 10016, USA.
Fu
Jie
J
States
Bradley A
BA
Ziff
Edward B
EB
D048868:Adaptor Proteins, Signal Transducing; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D022081:Cell Surface Extensions / Q000378:metabolism*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D017930:Genes, Reporter; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007424:Intracellular Fluid / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D046911:Macromolecular Substances; D008297:Male; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D051958:Nuclear Receptor Coactivator 2; D009928:Organ Specificity; D010169:Palmitic Acids / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C485566:GRIP2 protein, human; C118486:Grip2 protein, rat; D036341:Intercellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; D051958:Nuclear Receptor Coactivator 2; D010169:Palmitic Acids; D020033:Protein Isoforms; D012333:RNA, Messenger; D018091:Receptors, AMPA; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C104722:glutamate receptor ionotropic, AMPA 2