Through regulated exocytosis, material is transferred
between cells via the fusion of membrane vesicles. Synaptic vesicles mediate
transmission at chemical synapses. These vesicles bulge inward at the
presynaptic plasma membrane through a clathrin-coated pit. Invagination of the
membrane and pinching off forms a free vesicle, coated with clathrin, that can
be used for another round of release in the synapse after it sheds its clathrin
coat.
Research at the Alfonso laboratory centers around the question of how synaptic
vesicles are retrieved after they fuse with the plasma membrane. We utilize the
soil nematode Caenorhabditis elegans (C. elegans) as a model system for these
studies. Nematodes defective in neurotransmission, i.e. release, such as
mutants lacking the function of gene unc-11, are used to study synaptic vesicle
recycling. Phenotypically, unc-11 nematodes are defective in many behaviors
including locomotion, which is characterized as uncoordinated or Unc.
Furthermore, unc-11 animals are defective in synaptic vesicle size and synaptic
vesicle protein composition. Thus, we believe unc-11 functions in recycling of
synaptic vesicles at the plasma membrane.
To identify binding partners of the UNC-11 protein, I helped screen two cDNA
libraries using the Yeast Two-Hybrid approach. We have identified three
proteins as potential binding partners of the UNC-11A isoform; they include
heat shock protein 90, Hrs-2, and EAST. These three proteins are associated in
yeast cells. We are testing whether the interaction is also present in the
nematode. I am in the process of determining if these proteins also interact
with other UNC-11 isoforms.