The stimulatory effect of rabphilin 3a on regulated exocytosis from insulin-secreting cells does not require an association-dissociation cycle with membranes mediated by Rab 3

Détails

ID Serval
serval:BIB_94E15216ADBE
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
The stimulatory effect of rabphilin 3a on regulated exocytosis from insulin-secreting cells does not require an association-dissociation cycle with membranes mediated by Rab 3
Périodique
European Journal of Cell Biology
Auteur(s)
Arribas  M., Regazzi  R., Garcia  E., Wollheim  C. B., De Camilli  P.
ISSN
0171-9335 (Print)
Statut éditorial
Publié
Date de publication
11/1997
Volume
74
Numéro
3
Pages
209-16
Notes
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S. --- Old month value: Nov
Résumé
Rabphilin 3a is a Rab 3-GTP binding protein concentrated on secretory vesicles of neurons and endocrine cells. There is evidence that rabphilin 3a undergoes cycles of association-dissociation with membranes and that recruitment of rabphilin 3a to secretory vesicles is mediated by Rab 3a, suggesting that rabphilin 3a is a downstream effector of this Rab. In this study we have investigated whether a membrane-anchored form of rabphilin 3a mimics the action of rabphilin 3a on secretion and bypasses the need for Rab 3 function. Overexpression of both wild-type rabphilin 3a and of a transmembrane anchored form of rabphilin 3a stimulated (about 2-fold) evoked secretion of coexpressed human proinsulin from clonal HIT-T15 cells. A similar transmembrane-anchored protein which lacked the Rab 3 binding region stimulated secretion even more effectively. Unexpectedly, a rabphilin 3a deletion mutant missing the Rab 3 binding domain was also stimulatory on secretion, although a further deletion of rabphilin to exclude the first of the two proline-rich regions abolished its stimulatory effect. The first of these two mutants was primarily particulate, while the second mutant was primarily soluble, suggesting that the first proline-rich region of rabphilin 3a plays a role in targeting rabphilin to its site of action. We conclude that the action of rabphilin 3a can be independent of Rab 3 if other mechanisms produce a sufficient concentration of the protein in proximity of exocytotic sites. These results provide new evidence for a fundamental similarity in the mechanisms by which Ras and Rab GTPase produce their distinct physiological effects.
Mots-clé
Adaptor Proteins, Signal Transducing Amino Acid Sequence Animals CHO Cells *Calcium-Binding Proteins Cell Line Cricetinae *Exocytosis GTP-Binding Proteins/genetics/*metabolism Humans Membrane Glycoproteins/genetics/metabolism Molecular Sequence Data Nerve Tissue Proteins/genetics/*metabolism Proinsulin/genetics/*secretion Protein Precursors/genetics/secretion Rats Recombinant Fusion Proteins/genetics/metabolism Subcellular Fractions/metabolism Synaptotagmins Vesicular Transport Proteins *rab GTP-Binding Proteins rab3 GTP-Binding Proteins
Pubmed
Web of science
Création de la notice
24/01/2008 15:30
Dernière modification de la notice
03/03/2018 19:38
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