A role for calpactin in calcium-dependent exocytosis in adrenal chromaffin cells

Nature ◽  
1989 ◽  
Vol 340 (6231) ◽  
pp. 313-315 ◽  
Author(s):  
Shahid M. Ali ◽  
Michael J. Geisow ◽  
Robert D. Burgoyne
Keyword(s):  
Chromaffin Cells ◽  
Adrenal Chromaffin Cells ◽  
Calcium Dependent ◽  
Adrenal Chromaffin

scholarly journals Two distinct secretory vesicle–priming steps in adrenal chromaffin cells

2010 ◽  
Vol 190 (6) ◽  
pp. 1067-1077 ◽  
Author(s):  
Yuanyuan Liu ◽  
Claudia Schirra ◽  
Ludwig Edelmann ◽  
Ulf Matti ◽  
JeongSeop Rhee ◽  
...  
Keyword(s):  
Chromaffin Cells ◽  
Secretory Vesicle ◽  
Adrenal Chromaffin Cells ◽  
Attachment Protein ◽  
Calcium Dependent ◽  
Open Conformation ◽  
Large Dense Core Vesicles ◽  
Priming Process ◽  
Adrenal Chromaffin ◽  
Protein Attachment

Priming of large dense-core vesicles (LDCVs) is a Ca2+-dependent step by which LDCVs enter a release-ready pool, involving the formation of the soluble N-ethyl-maleimide sensitive fusion protein attachment protein (SNAP) receptor complex consisting of syntaxin, SNAP-25, and synaptobrevin. Using mice lacking both isoforms of the calcium-dependent activator protein for secretion (CAPS), we show that LDCV priming in adrenal chromaffin cells entails two distinct steps. CAPS is required for priming of the readily releasable LDCV pool and sustained secretion in the continued presence of high Ca2+ concentrations. Either CAPS1 or CAPS2 can rescue secretion in cells lacking both CAPS isoforms. Furthermore, the deficit in the readily releasable LDCV pool resulting from CAPS deletion is reversed by a constitutively open form of syntaxin but not by Munc13-1, a priming protein that facilitates the conversion of syntaxin to the open conformation. Our data indicate that CAPS functions downstream of Munc13s but also interacts functionally with Munc13s in the LDCV-priming process.

scholarly journals Doc2B acts as a calcium sensor for vesicle priming requiring synaptotagmin-1, Munc13-2 and SNAREs

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Sébastien Houy ◽  
Alexander J Groffen ◽  
Iwona Ziomkiewicz ◽  
Matthijs Verhage ◽  
Paulo S Pinheiro ◽  
...  
Keyword(s):  
Binding Sites ◽  
Chromaffin Cells ◽  
Protein Domain ◽  
Calcium Sensor ◽  
Adrenal Chromaffin Cells ◽  
Dynein Light Chain ◽  
C2 Domains ◽  
Calcium Dependent ◽  
Synaptotagmin 1 ◽  
Adrenal Chromaffin

Doc2B is a cytosolic protein with binding sites for Munc13 and Tctex-1 (dynein light chain), and two C2-domains that bind to phospholipids, Ca2+ and SNAREs. Whether Doc2B functions as a calcium sensor akin to synaptotagmins, or in other calcium-independent or calcium-dependent capacities is debated. We here show by mutation and overexpression that Doc2B plays distinct roles in two sequential priming steps in mouse adrenal chromaffin cells. Mutating Ca2+-coordinating aspartates in the C2A-domain localizes Doc2B permanently at the plasma membrane, and renders an upstream priming step Ca2+-independent, whereas a separate function in downstream priming depends on SNARE-binding, Ca2+-binding to the C2B-domain of Doc2B, interaction with ubMunc13-2 and the presence of synaptotagmin-1. Another function of Doc2B – inhibition of release during sustained calcium elevations – depends on an overlapping protein domain (the MID-domain), but is separate from its Ca2+-dependent priming function. We conclude that Doc2B acts as a vesicle priming protein.

Morphological Observations on the Granule Types in Rabbit Extra-Adrenal Chromaffin Cells.

1975 ◽  
Vol 33 ◽  
pp. 318-319
Author(s):  
Joe A. Mascorro ◽  
Robert D. Yates
Keyword(s):  
Chromaffin Cells ◽  
Sodium Phosphate ◽  
Ganglion Cells ◽  
Ultrastructural Level ◽  
Osmic Acid ◽  
Adrenal Chromaffin Cells ◽  
Potassium Iodate ◽  
Perfusion Fluid ◽  
New Zealand White Rabbits ◽  
Adrenal Chromaffin

Extra-adrenal chromaffin organs (abdominal paraganglia) constitute rich sources of catecholamines. It is believed that these bodies contain norepinephrine exclusively. However, the present workers recently observed epinephrine type granules in para- ganglion cells. This report investigates catecholamine containing granules in rabbit paraganglia at the ultrastructural level.New Zealand white rabbits (150-170 grams) were anesthetized with 50 mg/kg Nembutal (IP) and perfused with 3% glutaraldehyde buffered with 0.2M sodium phosphate, pH 7.3. The retroperitoneal tissue blocks were removed and placed in perfusion fluid for 4 hours. The abdominal paraganglia were dissected from the blocks, diced, washed in phosphate buffer and fixed in 1% osmic acid buffered with phosphate. In other animals, the glutaraldehyde perfused tissue blocks were immersed for 1 hour in 3% glutaraldehyde/2.5% potassium iodate buffered as before. The paraganglia were then diced, separated into two vials and washed in the buffer. A portion of this tissue received osmic acid fixation.

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