Developmental regulation and specific brain distribution of phosphorabphilin.
Protein kinases and phosphatases play an important role in modulating synaptic transmission. The synaptic protein rabphilin associates with synaptic vesicles through the small GTPase Rab3A, binds Ca(2+) and phospholipids, and interacts with cytoskeletal elements, yet its function remains controversial. In this study, we have generated phosphospecific antibodies and studied the developmental, subcellular, and brain distribution of rabphilin phosphorylated at serine-234 and serine-274. Our results show that phosphorabphilin is present in vivo under basal conditions in a specific subset of synapses. The phosphorylated rabphilin is abundant in the cerebellum, midbrain, and medulla; phosphorabphilin is specifically enriched in the climbing fiber synapses of the cerebellar cortex. Its developmental profile reveals a sharp and transient increase at approximately postnatal day 16, a period critical for the activity-dependent pruning of supernumerary climbing fibers in the cerebellum. We propose that the phosphorylation of rabphilin regulates neuronal activity through development and in a synapse-specific manner.
Foletti
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DL
Howard Hughes Medical Institute, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305-5428, USA.
Scheller
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RH
D048868:Adaptor Proteins, Signal Transducing; D000375:Aging / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000302:isolation & purification / Q000378:metabolism; D000918:Antibody Specificity; D015153:Blotting, Western; D001921:Brain / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D008526:Medulla Oblongata / Q000378:metabolism; D008636:Mesencephalon / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000276:immunology / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D011689:Purkinje Cells / Q000166:cytology / Q000378:metabolism; D051381:Rats; D012694:Serine / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism; D015854:Up-Regulation; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D020826:rab3A GTP-Binding Protein / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D000097624:Rabphilin-3A
D048868:Adaptor Proteins, Signal Transducing; D000906:Antibodies; D009419:Nerve Tissue Proteins; D012694:Serine; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D020826:rab3A GTP-Binding Protein; D000097624:Rabphilin-3A