Kinetic regulation of coated vesicle secretion.

Explorer Munc 18 / Syntaxin Interaction Kinetics Control Secretory Vesicle

Regulation of the Sar1 GTPase Cycle Is Necessary for Large Cargo Secretion from the Endoplasmic Reticulum

Proteins synthesized within the endoplasmic reticulum (ER) are transported to the Golgi via coat protein complex II (COPII)-coated vesicles. The formation of COPII-coated vesicles is regulated by the GTPase cycle of Sar1. Activated Sar1 is recruited to ER membranes and forms a pre-budding complex with cargoes and the inner-coat complex. The outer-coat complex then stimulates Sar1 inactivation a...

A putative heterotrimeric G protein inhibits the fusion of COPI-coated vesicles. Segregation of heterotrimeric G proteins from COPI-coated vesicles.

Heterotrimeric G proteins have been implicated in the regulation of intracellular protein transport, but their mechanism of action remains unclear. In vivo, secretion of chromogranin B, tagged with the green fluorescent protein, was inhibited by the addition of a general activator of trimeric G proteins (AlF4-) to stably transfected Vero cells and resulted in an accumulation of the tagged prote...

Molecular mechanisms of Sar/Arf GTPases in vesicular trafficking in yeast and plants

Small GTPase proteins play essential roles in the regulation of vesicular trafficking systems in eukaryotic cells. Two types of small GTPases, secretion-associated Ras-related protein (Sar) and ADP-ribosylation factor (Arf), act in the biogenesis of transport vesicles. Sar/Arf GTPases function as molecular switches by cycling between active, GTP-bound and inactive, GDP-bound forms, catalyzed by...

ADP ribosylation factor 1 mutants identify a phospholipase D effector region and reveal that phospholipase D participates in lysosomal secretion but is not sufficient for recruitment of coatomer I.

The small GTP-binding protein, ADP-ribosylation factor 1 (ARF1) is essential for the formation of coatomer-coated vesicles from the Golgi and is also an activator of phospholipase D (PLD). Moreover, ARF1-regulated PLD is part of the signal-transduction pathway that can lead to secretion. In this study, substitution and deletion mutants of ARF1 were tested for their ability to activate PLD. Thes...