scholarly journals Acidification of Serotonin-containing Secretory Vesicles Induced by a Plasma Membrane Calcium Receptor

1996 ◽  
Vol 271 (11) ◽  
pp. 6441-6450 ◽  
Author(s):  
Hadassah Tamir ◽  
Kuo-peing Liu ◽  
Mella Adlersberg ◽  
Shu-chi Hsiung ◽  
Michael D. Gershon
Keyword(s):  
Plasma Membrane ◽  
Secretory Vesicles ◽  
Calcium Receptor

Synaptotagmin-1: A Multi-Functional Protein that Mediates Vesicle Docking, Priming, and Fusion

2021 ◽  
Vol 22 ◽  
Author(s):  
Najeeb Ullah ◽  
Ezzouhra El Maaiden ◽  
Md. Sahab Uddin ◽  
Ghulam Md Ashraf
Keyword(s):  
Plasma Membrane ◽  
Secretory Granules ◽  
Secretory Vesicle ◽  
Neuroendocrine Cells ◽  
Snare Complex ◽  
Secretory Vesicles ◽  
Functional Protein ◽  
Vesicle Docking ◽  
Synaptotagmin 1

: The fusion of secretory vesicles with the plasma membrane depends on the assembly of v-SNAREs (VAMP2/synaptobrevin2) and t-SNAREs (SNAP25/syntaxin1) into the SNARE complex. Vesicles go through several upstream steps, referred to as docking and priming, to gain fusion competence. The vesicular protein synaptotagmin-1 (Syt-1) is the principal Ca2+ sensor for fusion in several central nervous system neurons and neuroendocrine cells and part of the docking complex for secretory granules. Syt-1 binds to the acceptor complex such as synaxin1, SNAP-25 on the plasma membrane to facilitate secretory vesicle docking, and upon Ca2+-influx promotes vesicle fusion. This review assesses the role of the Syt-1 protein involved in the secretory vesicle docking, priming, and fusion.

scholarly journals Secretory Pathway-Dependent Localization of the Saccharomyces cerevisiae Rho GTPase-Activating Protein Rgd1p at Growth Sites

2012 ◽  
Vol 11 (5) ◽  
pp. 590-600 ◽  
Author(s):  
Fabien Lefèbvre ◽  
Valérie Prouzet-Mauléon ◽  
Michel Hugues ◽  
Marc Crouzet ◽  
Aurélie Vieillemard ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Cell Cycle Progression ◽  
Secretory Pathway ◽  
Rho Gtpase ◽  
Secretory Vesicles ◽  
Gtpase Activating Protein ◽  
Content Type

ABSTRACT Establishment and maintenance of cell polarity in eukaryotes depends upon the regulation of Rho GTPases. In Saccharomyces cerevisiae , the Rho GTPase activating protein (RhoGAP) Rgd1p stimulates the GTPase activities of Rho3p and Rho4p, which are involved in bud growth and cytokinesis, respectively. Consistent with the distribution of Rho3p and Rho4p, Rgd1p is found mostly in areas of polarized growth during cell cycle progression. Rgd1p was mislocalized in mutants specifically altered for Golgi apparatus-based phosphatidylinositol 4-P [PtdIns(4)P] synthesis and for PtdIns(4,5)P 2 production at the plasma membrane. Analysis of Rgd1p distribution in different membrane-trafficking mutants suggested that Rgd1p was delivered to growth sites via the secretory pathway. Rgd1p may associate with post-Golgi vesicles by binding to PtdIns(4)P and then be transported by secretory vesicles to the plasma membrane. In agreement, we show that Rgd1p coimmunoprecipitated and localized with markers specific to secretory vesicles and cofractionated with a plasma membrane marker. Moreover, in vivo imaging revealed that Rgd1p was transported in an anterograde manner from the mother cell to the daughter cell in a vectoral manner. Our data indicate that secretory vesicles are involved in the delivery of RhoGAP Rgd1p to the bud tip and bud neck.

scholarly journals The Neurospora crassa exocyst complex tethers Spitzenkörper vesicles to the apical plasma membrane during polarized growth

2014 ◽  
Vol 25 (8) ◽  
pp. 1312-1326 ◽  
Author(s):  
Meritxell Riquelme ◽  
Erin L. Bredeweg ◽  
Olga Callejas-Negrete ◽  
Robert W. Roberson ◽  
Sarah Ludwig ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Neurospora Crassa ◽  
Hyphal Growth ◽  
Apical Plasma Membrane ◽  
Apical Region ◽  
Secretory Vesicles ◽  
Polarized Growth ◽  
Hyphal Morphogenesis ◽  
Exocyst Complex ◽  
Dynamic Formation

Fungal hyphae are among the most highly polarized cells. Hyphal polarized growth is supported by tip-directed transport of secretory vesicles, which accumulate temporarily in a stratified manner in an apical vesicle cluster, the Spitzenkörper. The exocyst complex is required for tethering of secretory vesicles to the apical plasma membrane. We determined that the presence of an octameric exocyst complex is required for the formation of a functional Spitzenkörper and maintenance of regular hyphal growth in Neurospora crassa. Two distinct localization patterns of exocyst subunits at the hyphal tip suggest the dynamic formation of two assemblies. The EXO-70/EXO-84 subunits are found at the peripheral part of the Spitzenkörper, which partially coincides with the outer macrovesicular layer, whereas exocyst components SEC-5, -6, -8, and -15 form a delimited crescent at the apical plasma membrane. Localization of SEC-6 and EXO-70 to the plasma membrane and the Spitzenkörper, respectively, depends on actin and microtubule cytoskeletons. The apical region of exocyst-mediated vesicle fusion, elucidated by the plasma membrane–associated exocyst subunits, indicates the presence of an exocytotic gradient with a tip-high maximum that dissipates gradually toward the subapex, confirming the earlier predictions of the vesicle supply center model for hyphal morphogenesis.

scholarly journals Yeast Cdc42 functions at a late step in exocytosis, specifically during polarized growth of the emerging bud

2001 ◽  
Vol 155 (4) ◽  
pp. 581-592 ◽  
Author(s):  
Joan E. Adamo ◽  
John J. Moskow ◽  
Amy S. Gladfelter ◽  
Domenic Viterbo ◽  
Daniel J. Lew ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Temperature Sensitive ◽  
Secretory Vesicles ◽  
Polarized Growth ◽  
Vesicle Docking ◽  
Actin Organization ◽  
Late Step ◽  
Rho Family ◽  
Localization Data

The Rho family GTPase Cdc42 is a key regulator of cell polarity and cytoskeletal organization in eukaryotic cells. In yeast, the role of Cdc42 in polarization of cell growth includes polarization of the actin cytoskeleton, which delivers secretory vesicles to growth sites at the plasma membrane. We now describe a novel temperature-sensitive mutant, cdc42-6, that reveals a role for Cdc42 in docking and fusion of secretory vesicles that is independent of its role in actin polarization. cdc42-6 mutants can polarize actin and deliver secretory vesicles to the bud, but fail to fuse those vesicles with the plasma membrane. This defect is manifested only during the early stages of bud formation when growth is most highly polarized, and appears to reflect a requirement for Cdc42 to maintain maximally active exocytic machinery at sites of high vesicle throughput. Extensive genetic interactions between cdc42-6 and mutations in exocytic components support this hypothesis, and indicate a functional overlap with Rho3, which also regulates both actin organization and exocytosis. Localization data suggest that the defect in cdc42-6 cells is not at the level of the localization of the exocytic apparatus. Rather, we suggest that Cdc42 acts as an allosteric regulator of the vesicle docking and fusion apparatus to provide maximal function at sites of polarized growth.

scholarly journals Cell Secretion: Current Structural and Biochemical Insights

2010 ◽  
Vol 10 ◽  
pp. 2054-2069 ◽  
Author(s):  
Saurabh Trikha ◽  
Elizabeth C. Lee ◽  
Aleksandar M. Jeremic
Keyword(s):  
Plasma Membrane ◽  
Secretory Vesicles ◽  
Intercellular Signaling ◽  
Cell Secretion ◽  
Membrane Structures ◽  
Calcium Dependent ◽  
Cell Plasma ◽  
Membrane Bound ◽  
And Control ◽  
Fusion Pores

Essential physiological functions in eukaryotic cells, such as release of hormones and digestive enzymes, neurotransmission, and intercellular signaling, are all achieved by cell secretion. In regulated (calcium-dependent) secretion, membrane-bound secretory vesicles dock and transiently fuse with specialized, permanent, plasma membrane structures, called porosomes or fusion pores. Porosomes are supramolecular, cup-shaped lipoprotein structures at the cell plasma membrane that mediate and control the release of vesicle cargo to the outside of the cell. The sizes of porosomes range from 150nm in diameter in acinar cells of the exocrine pancreas to 12nm in neurons. In recent years, significant progress has been made in our understanding of the porosome and the cellular activities required for cell secretion, such as membrane fusion and swelling of secretory vesicles. The discovery of the porosome complex and the molecular mechanism of cell secretion are summarized in this article.

Insulin Vesicle Release: Walk, Kiss, Pause … Then Run

Physiology ◽  
2006 ◽  
Vol 21 (3) ◽  
pp. 189-196 ◽  
Author(s):  
Guy A. Rutter ◽  
Elaine V. Hill
Keyword(s):  
Plasma Membrane ◽  
Molecular Mechanisms ◽  
Secretory Vesicles ◽  
Pancreatic Β Cell ◽  
Current Interest ◽  
Contributing Factors ◽  
Β Cell ◽  
Vesicle Release ◽  
Reversible Process

The mechanisms by which insulin-containing dense core secretory vesicles approach and finally fuse with the plasma membrane are of considerable current interest: defects in these processes may be one of the contributing factors to Type 2 diabetes. In this review, we discuss the molecular mechanisms involved in vesicle trafficking within the pancreatic β-cell and the mechanisms whereby these may be regulated. We then go on to describe recent evidence that suggests that vesicle fusion at the plasma membrane is a partly reversible process (“kiss and run” or “cavity recapture”). We propose that vesicles may participate in a exo-endocytotic cycle in which a proportion of those that have already undergone an interaction with the plasma membrane may exchange exocytotic machinery with maturing vesicles.

scholarly journals Two subunits of the exocyst, Sec3p and Exo70p, can function exclusively on the plasma membrane

2018 ◽  
Vol 29 (6) ◽  
pp. 736-750 ◽  
Author(s):  
Dongmei Liu ◽  
Xia Li ◽  
David Shen ◽  
Peter Novick
Keyword(s):  
Plasma Membrane ◽  
The Other ◽  
Secretory Vesicles ◽  
Endocytic Recycling ◽  
C Terminus ◽  
Tm Domain

The exocyst is an octameric complex that tethers secretory vesicles to the plasma membrane in preparation for fusion. We anchored each subunit with a transmembrane (TM) domain at its N- or C-terminus. Only N-terminally anchored TM-Sec3p and C-terminally anchored Exo70p-TM proved functional. These findings orient the complex with respect to the membrane and establish that Sec3p and Exo70p can function exclusively on the membrane. The functions of TM-Sec3p and Exo70p-TM were largely unaffected by blocks in endocytic recycling, suggesting that they act on the plasma membrane rather than on secretory vesicles. Cytosolic pools of the other exocyst subunits were unaffected in TM-sec3 cells, while they were partially depleted in exo70-TM cells. Blocking actin-dependent delivery of secretory vesicles in act1-3 cells results in loss of Sec3p from the purified complex. Our results are consistent with a model in which Sec3p and Exo70p can function exclusively on the plasma membrane while the other subunits are brought to them on secretory vesicles.

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