rab3A attachment to the synaptic vesicle membrane mediated by a conserved polyisoprenylated carboxy-terminal sequence

Johnston, Patricia A.; Archer, Branch T.; Robinson, K. L.; Mignery, Gregory A.; Jahn, Reinhard; Südhof, Thomas C.

doi:10.1016/0896-6273(91)90078-e

Cited by 95 publications

(51 citation statements)

References 26 publications

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“…This conservation of sequence is restricted to the central 190 amino acid core of the protein, which retains over 88% identity with Drosophila rab3. By contrast, the N-and C-terminal regions of C. elegans rab3 diverge significantly from both Drosophila and vertebrate rab3 members, except for the presumptive CXC prenylation site at the C terminus (Johnston et al, 1991). The gene was named rab-3 in accordance with C. elegans nomenclature guidelines (Horvitz et al, 1979).…”

Section: Resultsmentioning

confidence: 99%

Caenorhabditis elegans rab-3Mutant Synapses Exhibit Impaired Function and Are Partially Depleted of Vesicles

et al. 1997

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Rab molecules regulate vesicular trafficking in many different exocytic and endocytic transport pathways in eukaryotic cells. In neurons, rab3 has been proposed to play a crucial role in regulating synaptic vesicle release. To elucidate the role of rab3 in synaptic transmission, we isolated and characterized Caenorhabditis elegans rab-3 mutants. Similar to the mouse rab3A mutants, these mutants survived and exhibited only mild behavioral abnormalities. In contrast to the mouse mutants, synaptic transmission was perturbed in these animals. Extracellular electrophysiological recordings revealed that synaptic transmission in the pharyngeal nervous system was impaired. Furthermore, rab-3 animals were resistant to the acetylcholinesterase inhibitor aldicarb, suggesting that cholinergic transmission was generally depressed. Last, synaptic vesicle populations were redistributed in rab-3 mutants. In motor neurons, vesicle populations at synapses were depleted to 40% of normal levels, whereas in intersynaptic regions of the axon, vesicle populations were elevated. On the basis of the morphological defects at neuromuscular junctions, we postulate that RAB-3 may regulate recruitment of vesicles to the active zone or sequestration of vesicles near release sites.

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Section: Resultsmentioning

confidence: 99%

Caenorhabditis elegans rab-3Mutant Synapses Exhibit Impaired Function and Are Partially Depleted of Vesicles

et al. 1997

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“…1). It should be noted that in transiently transfected 293 cells, the post-translational geranylgeranylation of Rab3 proteins is incomplete, presumably because the overexpressed proteins overwhelm the geranylgeranylation capacity of the cells (41). As a result, an immature lower band and a mature upper band are observed for Rab3 proteins in transfected 293 cells but not in rat tissue samples (Fig.…”

Section: Generation Of Isoform-specific Rab3mentioning

confidence: 98%

“…To elucidate the mechanism of this inhibition, we first tested whether membrane attachment of Rab3A is essential for inhibition by comparing wild type Rab3A with a mutant lacking the C terminus, which is modified by geranylgeranylation (41). The C-terminally truncated Rab3A was as effective as the wild type in inhibiting Ca 2ϩ -triggered exocytosis (Fig.…”

Section: Rab3 Proteins Inhibit Ca 2ϩ -Triggered Exocytosis In Pc12 Cementioning

confidence: 99%

“…This was done to increase the sensitivity of detection of Rab3 proteins. Rab3 proteins are hydrophobic, because of their C-terminal geranylgera-nyl modification, and are co-purified with membrane proteins by Triton X-114 extraction (41,42). We then measured the amount of each Rab3 protein relative to a standard amount of heterologously expressed Rab3 analyzed on the same blot; immunoblotting signals were quantified using 125 I-labeled secondary antibodies and detected by phosphorimaging.…”

Section: Generation Of Isoform-specific Rab3mentioning

confidence: 99%

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Localization Versus Function of Rab3 Proteins

Schlüter

Khvotchev

Jahn

et al. 2002

Journal of Biological Chemistry

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150

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Rab3A, Rab3B, Rab3C, and Rab3D constitute a family of GTP-binding proteins that are implicated in regulated exocytosis. Various localizations and distinct functions have been proposed for different and occasionally even for the same Rab3 protein. This is exemplified by studies demonstrating that deletion of Rab3A in knock-out mice results in dysregulation of the final stages of exocytosis, whereas overexpression of Rab3A in neuroendocrine cells causes nearly complete inhibition of Ca 2؉-triggered exocytosis. We have now examined the properties of all Rab3 proteins in the same assays, with the long-term goal of identifying a common conceptual framework for their functions. Using quantitative immunoblotting, we found that all four Rab3 proteins were expressed in brain and endocrine tissues, although at widely different levels. Rab3A, Rab3B, and Rab3C co-localized to synaptic and secretory vesicles consistent with potential redundancy, whereas Rab3D was expressed at high levels only in the endocrine pituitary (where it was more abundant than Rab3A, Rab3B, and Rab3C combined), in exocrine glands, and in adipose tissue. In transfected PC12 cells, all four Rab3 proteins strongly inhibited Ca 2؉ -triggered exocytosis. Except for a mutation that fixes Rab3 into a permanently GDP-bound state, all Rab3 mutations tested had no effect on this inhibition, including a mutation in the calmodulin-binding site that was described as inactivating (Coppola, T., Perret-Menoud, V., Lü thi, S., Farnsworth, C. C., Glomset, J. A., and Regazzi, R. (1999) EMBO J. 18, 5885-5891). Unexpectedly, overexpression of wild type Rab3A and permanently GTP-bound mutant Rab3A in PC12 cells caused a loss of secretory vesicles and an increase in constitutive, Ca 2؉ -independent exocytosis that correlated with the inhibition of regulated Ca 2؉ -triggered exocytosis. Our data indicate that overexpression of Rab3 in PC12 cells impairs the normal control of the final step in exocytosis, thereby converting the regulated secretory pathway into a constitutive pathway. These results offer an hypothesis that reconciles Rab3 transfection and knockout studies by suggesting that Rab3 functions as a gatekeeper of a late stage in exocytosis.

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“…More specifically, the capacity to target recycling vesicles again to the active zone may be an important factor during high activity of the terminal. The association of rab3A to small synaptic vesicles depends on hydrophobic modifications of the protein (Musha et al, 1992;Farnsworth et al, 1991;Johnston et al, 1991), which may function as a membrane anchor for the protein. Following exocytosis, the amount of rab3A associated with vesicles is decreased (Fischer von Mollard et al, 1990).…”

Section: The Availability Of Transmitters For Releasementioning

confidence: 99%