Mutational Analysis of Rab3 Function for Controlling Active Zone Protein Composition at the Drosophila Neuromuscular Junction

PLoS One. 2015 Aug 28;10(8):e0136938. doi: 10.1371/journal.pone.0136938. eCollection 2015.


At synapses, the release of neurotransmitter is regulated by molecular machinery that aggregates at specialized presynaptic release sites termed active zones. The complement of active zone proteins at each site is a determinant of release efficacy and can be remodeled to alter synapse function. The small GTPase Rab3 was previously identified as playing a novel role that controls the distribution of active zone proteins to individual release sites at the Drosophila neuromuscular junction. Rab3 has been extensively studied for its role in the synaptic vesicle cycle; however, the mechanism by which Rab3 controls active zone development remains unknown. To explore this mechanism, we conducted a mutational analysis to determine the molecular and structural requirements of Rab3 function at Drosophila synapses. We find that GTP-binding is required for Rab3 to traffick to synapses and distribute active zone components across release sites. Conversely, the hydrolytic activity of Rab3 is unnecessary for this function. Through a structure-function analysis we identify specific residues within the effector-binding switch regions that are required for Rab3 function and determine that membrane attachment is essential. Our findings suggest that Rab3 controls the distribution of active zone components via a vesicle docking mechanism that is consistent with standard Rab protein function.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Binding Sites
  • DNA Mutational Analysis / methods*
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / metabolism*
  • Neuromuscular Junction / metabolism*
  • Neuromuscular Junction / physiology
  • Protein Binding
  • Synaptic Vesicles / metabolism
  • rab3 GTP-Binding Proteins / chemistry
  • rab3 GTP-Binding Proteins / genetics*
  • rab3 GTP-Binding Proteins / metabolism*


  • BRP protein, Drosophila
  • Drosophila Proteins
  • Rab3 protein, Drosophila
  • rab3 GTP-Binding Proteins

Associated data

  • Dryad/10.5061/dryad.ST6H9