Transport route for synaptobrevin via a novel pathway of insertion into the endoplasmic reticulum membrane.
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Kutay U, Ahnert-Hilger G, Hartmann E, Wiedenmann B, Rapoport TA
Transport route for synaptobrevin via a novel pathway of insertion into the endoplasmic reticulum membrane.
EMBO J. 1995 Jan 16;14(2):217-23.
- PubMed ID
- 7835332 [ View in PubMed]
- Abstract
Synaptobrevin/vesicle-associated membrane protein is one of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. It is proposed to provide specificity for the targeting and fusion of vesicles with the plasma membrane. It belongs to a class of membrane proteins which lack a signal sequence and contain a single hydrophobic segment close to their C-terminus, leaving most of the polypeptide chain in the cytoplasm (tail-anchored). We show that in neuroendocrine PC12 cells, synaptobrevin is not directly incorporated into the target organelle, synaptic-like vesicles. Rather, it is first inserted into the endoplasmic reticulum (ER) membrane and is then transported via the Golgi apparatus. Its insertion into the ER membrane in vitro occurs post-translationally, is dependent on ATP and results in a trans-membrane orientation of the hydrophobic tail. Membrane integration requires ER protein(s) different from the translocation components needed for proteins with signal sequences, thus suggesting a novel mechanism of insertion.