Functional regions of the presynaptic cytomatrix protein bassoon: significance for synaptic targeting and cytomatrix anchoring.
Exocytosis of neurotransmitter from synaptic vesicles is restricted to specialized sites of the presynaptic plasma membrane called active zones. A complex cytomatrix of proteins exclusively assembled at active zones, the CAZ, is thought to form a molecular scaffold that organizes neurotransmitter release sites. Here, we have analyzed synaptic targeting and cytomatrix association of Bassoon, a major scaffolding protein of the CAZ. By combining immunocytochemistry and transfection of cultured hippocampal neurons, we show that the central portion of Bassoon is crucially involved in synaptic targeting and CAZ association. An N-terminal region harbors a distinct capacity for N-myristoylation-dependent targeting to synaptic vesicle clusters, but is not incorporated into the CAZ. Our data provide the first experimental evidence for the existence of distinct functional regions in Bassoon and suggest that a centrally located CAZ targeting function may be complemented by an N-terminal capacity for targeting to membrane-bounded synaptic organelles.
Dresbach
Thomas
T
Leibniz Institute for Neurobiology, Brenneckestrasse 6, D-39118, Magdeburg, Germany.
Hempelmann
Anne
A
Spilker
Christina
C
tom Dieck
Susanne
S
Altrock
Wilko D
WD
Zuschratter
Werner
W
Garner
Craig C
CC
Gundelfinger
Eckart D
ED
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D005333:Fetus; D006624:Hippocampus / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D007150:Immunohistochemistry; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D015388:Organelles / Q000235:genetics / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins; D013570:Synaptic Membranes / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D014162:Transfection
C113688:Bsn protein, rat; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins