First published online March 23, 2005
Journal of Cell Science 118, 705e (2005)
© The Company of Biologists Limited
Sorting out the synaptotagmins
Synaptotagmins (Syts) are highly conserved, integral membrane proteins. In neuronal cells, Syt I and Syt II localize to synaptic vesicles, where they mediate Ca2+-triggered exocytosis; in non-neuronal secretory cells, such as mast cells, Syt I and Syt II localize to secretory granules and late endosomes/lysosomes, respectively. On p. 1363, Ronit Sagi-Eisenberg and colleagues investigate the trafficking of these proteins in the rat mast cell line RBL-2H3. They show that both proteins pass through the plasma membrane on their way from the trans-Golgi network to their target secretory granules and that endocytosis is required for Syt I and Syt II to reach their final destinations. Experiments using chimeric proteins indicate that the lumenal domains of Syt I and Syt II control whether the proteins remain at the plasma membrane or are internalized. Finally, in contrast to the N-glycosylation that controls Syt trafficking in neuronal cells, the authors identify O-glycosylation as the post-translation modification that controls trafficking in RBL-2H3 cells and, they suggest, in other non-neuronal secretory cells.
Related articles in JCS:
- O-glycosylation is essential for intracellular targeting of synaptotagmins I and II in non-neuronal specialized secretory cells
- Yafit Atiya-Nasagi, Hila Cohen, Ora Medalia, Mitsunori Fukudan, and Ronit Sagi-Eisenberg
JCS 2005 118: 1363-1372.
[Abstract]
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