Synaptotagmin Research Articles

The Products of theDrosophila stonedLocus Interact with Synaptic Vesicles via Synaptotagmin

The stoned locus of Drosophila melanogaster encodes two novel proteins, stonedA (STNA) and stonedB (STNB), both of which are expressed in the nervous system. Flies with defects at the stoned locus have abnormal behavior and altered synaptic transmission. Genetic interactions, in particular with the shibire (dynamin) mutation, indicated a presynaptic function for stoned and suggested an involvement in vesicle cycling. Immunological studies revealed colocalization of the stoned proteins at the neuromuscular junction with the integral synaptic vesicle protein synaptotagmin (SYT). We show here that stoned interacts genetically with synaptotagmin to produce a lethal phenotype. The STNB protein is found by co-immunoprecipitation to be associated with synaptic vesicles, and glutathione S-transferase pull-downs demonstrate an in vitro interaction between the micro2-homology domain of STNB and the C2B domain of the SYTI isoform. The STNA protein is also found in association with vesicles, and it too exhibits an in vitro association with SYTI. However, we find that the bulk of STNA is in a nonmembranous fraction. By using the shibire mutant to block endocytosis, STNB is shown to be present on some synaptic vesicles before exocytosis. However, STNB is not associated with all synaptic vesicles. We hypothesize that STNB specifies a subset of synaptic vesicles with a role in the synaptic vesicle cycle that is yet to be determined.

Lack of a docking mechanism for neurotransmitter release in the aganglionic segment of bowel in patients with Hirschsprung's disease.

We examined immunohistochemically the expression and localisation of synapse-associated proteins, syntaxin (SNT) and synaptotagmin (STG) in the entire resected specimens of colon obtained at the time of pull-through operation from 15 patients with Hirschsprung's disease (HD) and 6 age-matched controls. Both antibodies showed a similar pattern of staining. In the normal colon and ganglionic colon from HD, there was strong reactivity in the submucous and myenteric plexuses in addition to staining of nerve fibres in the smooth-muscle layers. In the aganglionic colon, there was an absence or marked decrease in SNT and STG-positive nerve fibres in the smooth-muscle layers and in hypertrophic nerve trunks. Our data indicate that important proteins necessary for the docking of synaptic vesicles at the presynaptic plasma membrane are lost in fibres innervating the smooth muscle of HD and suggest that abnormal neurotransmission may have a role in the maintenance of muscle spasticity.

312 Effect of inositol-6-phosphate on interaction between syntaxin and synaptotagmin

312 Effect of inositol-6-phosphate on interaction between syntaxin and synaptotagmin