Document Detail

Gamma-amino butyric acid (GABA) release in the ciliated protozoon Paramecium occurs by neuronal-like exocytosis.
MedLine Citation:
PMID:  20348336     Owner:  NLM     Status:  MEDLINE    
Paramecium primaurelia expresses a significant amount of gamma-amino butyric acid (GABA). Paramecia possess both glutamate decarboxylase (GAD)-like and vesicular GABA transporter (vGAT)-like proteins, indicating the ability to synthesize GABA from glutamate and to transport GABA into vesicles. Using antibodies raised against mammalian GAD and vGAT, bands with an apparent molecular weight of about 67 kDa and 57 kDa were detected. The presence of these bands indicated a similarity between the proteins in Paramecium and in mammals. VAMP, syntaxin and SNAP, putative proteins of the release machinery that form the so-called SNARE complex, are present in Paramecium. Most VAMP, syntaxin and SNAP fluorescence is localized in spots that vary in size and density and are primarily distributed near the plasma membrane. Antibodies raised against mammal VAMP-3, sintaxin-1 or SNAP-25 revealed protein immunoblot bands having molecular weights consistent with those observed in mammals. Moreover, P. primaurelia spontaneously releases GABA into the environment, and this neurotransmitter release significantly increases after membrane depolarization. The depolarization-induced GABA release was strongly reduced not only in the absence of extracellular Ca(2+) but also by pre-incubation with bafilomycin A1 or with botulinum toxin C1 serotype. It can be concluded that GABA occurs in Paramecium, where it is probably stored in vesicles capable of fusion with the cell membrane; accordingly, GABA can be released from Paramecium by stimulus-induced, neuronal-like exocytotic mechanisms.
P Ramoino; M Milanese; S Candiani; A Diaspro; M Fato; C Usai; G Bonanno
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  213     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-03-29     Completed Date:  2010-07-08     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1251-8     Citation Subset:  IM    
Department for the Study of Territory and its Resources (DIP.TE.RIS.), University of Genoa, Corso Europa 26, Genoa, Italy.
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MeSH Terms
Amino Acid Sequence
Botulinum Toxins / pharmacology
Exocytosis / drug effects,  physiology*
Glutamate Decarboxylase / metabolism
Molecular Sequence Data
Paramecium / drug effects,  physiology*
Protozoan Proteins / genetics,  metabolism
Qa-SNARE Proteins / metabolism
SNARE Proteins / genetics,  metabolism
Sequence Alignment
Vesicular Transport Proteins / metabolism
gamma-Aminobutyric Acid / metabolism*
Reg. No./Substance:
0/Botulinum Toxins; 0/Protozoan Proteins; 0/Qa-SNARE Proteins; 0/SNARE Proteins; 0/Vesicular Transport Proteins; 0/botulinum toxin type C; 56-12-2/gamma-Aminobutyric Acid; EC Decarboxylase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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