Characterisation of microtubule-associated proteins at the synapse: absence of MAP 2.
The high molecular weight microtubule-associated proteins MAP 1 and MAP 2 are major components of brain cytosol and can be readily identified using polyacrylamide gel electrophoresis on the basis of heat-stability and co-sedimentation with microtubules. An examination of synaptosomal cytosol, synaptic plasma membrane and postsynaptic density fractions showed that MAP 2 is absent from these fractions and thus from both pre- and postsynaptic sites. All of the fractions contained polypeptides that comigrated with MAP 1 and a MAP 1 like polypeptide was identified in a microtubule preparation from synaptosomal cytosol. The absence of MAP 2 from synaptosomal cytosol was confirmed by immunoblotting using an antibody directed against MAP 2. Immunocytochemistry using this antibody showed that MAP 2 was present in cell bodies and dendrites but absent from axons.
Burgoyne
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Laboratory of Biological Ultrastructure, National Institute for Medical Research, Mill Hill, London NW7 1AA/United Kingdom.
Cumming
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R
D000818:Animals; D001369:Axons / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis*; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism
D008869:Microtubule-Associated Proteins; D010455:Peptides