Characterization of a novel synapse-specific protein. I. Developmental expression and cellular localization of the F1-20 protein and mRNA.
A molecular description of the nerve terminal will be required to understand synaptic function fully. The goals of this study were to contribute toward such a description by characterizing a novel synapse-specific protein. A monoclonal antibody library was screened for antibodies to synaptic proteins. The antibodies were then used to isolate cDNA clones by expression screening. Here we report a detailed characterization of the protein reactive with monoclonal antibody F1-20. Immunohistochemical and biochemical analyses revealed that the F1-20 protein is synapse associated. Western blot analyses revealed that the F1-20 protein is a brain-specific polypeptide with an apparent molecular weight on SDS-PAGE of 190,000 Da. Northern blot analyses indicated that probes generated from an F1-20 cDNA clone hybridize to a single brain-specific mRNA of approximately 4.8 kilobases. In situ hybridization experiments demonstrated that F1-20 mRNA expression is neuronal specific. Northern and Western blot analyses indicated that F1-20 mRNA levels increase abruptly at postnatal day 4 and protein levels increase abruptly at postnatal day 7. This corresponds to a period of active synaptogenesis and synaptic maturation in the mouse CNS. We characterized the neuroanatomical distribution of the F1-20 protein by immunohistochemistry, and of the F1-20 mRNA by in situ hybridization. We found that the F1-20 mRNA and protein are expressed nonuniformly in brain. Variation in the expression of the F1-20 protein is complex and reveals patterns also exhibited by probes directed against other synapse-associated molecules. The highest levels of F1-20 protein are found in the cortically organized regions of the brain. The highest levels of F1-20 mRNA are found in long-distance projection neurons. There is also variation in the expression of F1-20 mRNA between different classes of large output neuron, as well as extensive variation in the expression of F1-20 mRNA between different nuclear groups.
Sousa
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Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260.
Tannery
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Zhou
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Lafer
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D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000911:Antibodies, Monoclonal; D001921:Brain / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D034041:Monomeric Clathrin Assembly Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D010750:Phosphoproteins; D012333:RNA, Messenger / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D034041:Monomeric Clathrin Assembly Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C439023:clathrin assembly protein AP180