Related Experiment Video
Updated: Aug 29, 2026

Assessing the Secretory Capacity of Pancreatic Acinar Cells
Published on: August 28, 2014
Roles of Munc18-3 in amylase release from rat parotid acinar cells
Akane Imai1, Tomoko Nashida, Hiromi Shimomura
1Department of Biochemistry, School of Dentistry at Niigata, The Nippon Dental University, 1-8 Hamaura-cho, Niigata 951-8580, Japan. imaiak@ngt.ndu.ac.jp
Abstract:
Several "soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor" (SNARE) proteins have been identified in rat parotid acinar cells, including VAMP-2, syntaxin 4, and SNAP-23. Furthermore, an association between Munc18c (Munc18-3) and syntaxin 4 has been reported. However, the role of Munc18-3 in secretory granule exocytosis on parotid acinar cells remains unclear. In the present study, we investigated the role of Munc18-3 in rat parotid acinar cells. Munc18-3 was localized on the apical plasma membrane where exocytosis occurs and interacted with syntaxin 4. Anti-Munc18-3 antibody dose-dependently decreased isoproterenol (IPR)-induced amylase release from SLO-permeabilized parotid acinar cells. Furthermore, stimulation of the acinar cells with IPR induced translocation of Munc18-3 from the plasma membrane to the cytosol. Munc-18-3 was not phosphorylated by a catalytic subunit of protein kinase (PK) A but phosphorylated by PKC. Treatment of the plasma membrane with PKC but not PKA induced displacement of Munc18-3 from the membrane. The results indicate that Munc18-3 regulates exocytosis in the acinar cells for IPR-induced amylase release and that phosphorylation of Munc18-3 by PKA is not involved in the mechanism.
Related Concept Videos
Overview of Secretory Vesicles
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
Pinching-off of Coated Vesicles
Rab Proteins
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Tail-anchoring of Proteins in the ER Membrane
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...

