Differential expression of two novel Munc13 proteins in rat brain.
Munc13-1, a mammalian homologue of Caenorhabditis elegans unc-13p, is a presynaptic phorbol ester receptor that enhances neurotransmitter release. In the present study we analysed the regional, cellular and subcellular expression patterns in rat of two novel Munc13 proteins, Munc13-2 and Munc13-3. We demonstrate by hybridization in situ that Munc13-1 mRNA is expressed throughout the brain, whereas Munc13-2 mRNA is preferentially present in rostral brain regions, and Munc13-3 mRNA in caudal areas. In an analysis of subcellular brain fractions with isoform-specific antibodies, we show that the novel Munc13 proteins are enriched in synapses. Immunocytochemical examination of rat cerebellar sections indicates that Munc13-3, like Munc13-1, is concentrated in presynaptic terminals. Our results characterize Munc13 proteins as a family of neuron-specific, synaptic molecules that bind to syntaxin, an essential mediator of neurotransmitter release. Munc13-2 and Munc13-3 are expressed in a complementary fashion and might act in concert with Munc13-1 to modulate neurotransmitter release.
Augustin
I
I
Max-Planck-Institut für experimentelle Medizin, Abteilung Molekulare Neurobiologie, Hermann-Rein-Strasse 3, D-37075 Göttingen, Germany.
Betz
A
A
Herrmann
C
C
Jo
T
T
Brose
N
N
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity; D050765:Qa-SNARE Proteins; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013347:Subcellular Fractions / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D012333:RNA, Messenger; C103912:Unc13a protein, rat; C485549:Unc13b protein, mouse; C117991:Unc13b protein, rat; C485550:Unc13c protein, mouse; C117992:Unc13c protein, rat