scholarly journals Ca2+-Triggered Simultaneous Membrane Penetration of the Tandem C2-Domains of Synaptotagmin I

2006 ◽  
Vol 91 (5) ◽  
pp. 1767-1777 ◽  
Author(s):  
Enfu Hui ◽  
Jihong Bai ◽  
Edwin R. Chapman
Keyword(s):  
Membrane Penetration ◽  
C2 Domains ◽  
Synaptotagmin I

scholarly journals The C2b Domain of Synaptotagmin Is a Ca2+–Sensing Module Essential for Exocytosis

2000 ◽  
Vol 150 (5) ◽  
pp. 1125-1136 ◽  
Author(s):  
Radhika C. Desai ◽  
Bimal Vyas ◽  
Cynthia A. Earles ◽  
J. Troy Littleton ◽  
Judith A. Kowalchyck ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Pc12 Cells ◽  
Conformational Changes ◽  
Cytoplasmic Domain ◽  
Dominant Negative ◽  
Fusion Pore ◽  
Vesicle Membrane ◽  
C2 Domains ◽  
Essential Step ◽  
Synaptotagmin I

The synaptic vesicle protein synaptotagmin I has been proposed to serve as a Ca2+ sensor for rapid exocytosis. Synaptotagmin spans the vesicle membrane once and possesses a large cytoplasmic domain that contains two C2 domains, C2A and C2B. Multiple Ca2+ ions bind to the membrane proximal C2A domain. However, it is not known whether the C2B domain also functions as a Ca2+-sensing module. Here, we report that Ca2+ drives conformational changes in the C2B domain of synaptotagmin and triggers the homo- and hetero-oligomerization of multiple isoforms of the protein. These effects of Ca2+ are mediated by a set of conserved acidic Ca2+ ligands within C2B; neutralization of these residues results in constitutive clustering activity. We addressed the function of oligomerization using a dominant negative approach. Two distinct reagents that block synaptotagmin clustering potently inhibited secretion from semi-intact PC12 cells. Together, these data indicate that the Ca2+-driven clustering of the C2B domain of synaptotagmin is an essential step in excitation-secretion coupling. We propose that clustering may regulate the opening or dilation of the exocytotic fusion pore.

scholarly journals Negative Coupling as a Mechanism for Signal Propagation between C2 Domains of Synaptotagmin I

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e46748 ◽  
Author(s):  
Michael E. Fealey ◽  
Jacob W. Gauer ◽  
Sarah C. Kempka ◽  
Katie Miller ◽  
Kamakshi Nayak ◽  
...  
Keyword(s):  
Signal Propagation ◽  
C2 Domains ◽  
Synaptotagmin I ◽  
Negative Coupling

scholarly journals The tandem C2 domains of synaptotagmin contain redundant Ca2+ binding sites that cooperate to engage t-SNAREs and trigger exocytosis

2001 ◽  
Vol 154 (6) ◽  
pp. 1117-1124 ◽  
Author(s):  
Cynthia A. Earles ◽  
Jihong Bai ◽  
Ping Wang ◽  
Edwin R. Chapman
Keyword(s):  
Membrane Fusion ◽  
Real Time ◽  
Pc12 Cells ◽  
Binding Sites ◽  
C2 Domain ◽  
C2 Domains ◽  
Synaptotagmin I ◽  
Target Membrane ◽  
Complete Disruption

Real-time voltammetry measurements from cracked PC12 cells were used to analyze the role of synaptotagmin–SNARE interactions during Ca2+-triggered exocytosis. The isolated C2A domain of synaptotagmin I neither binds SNAREs nor inhibits norepinephrine secretion. In contrast, two C2 domains in tandem (either C2A-C2B or C2A-C2A) bind strongly to SNAREs, displace native synaptotagmin from SNARE complexes, and rapidly inhibit exocytosis. The tandem C2 domains of synaptotagmin cooperate via a novel mechanism in which the disruptive effects of Ca2+ ligand mutations in one C2 domain can be partially alleviated by the presence of an adjacent C2 domain. Complete disruption of Ca2+-triggered membrane and target membrane SNARE interactions required simultaneous neutralization of Ca2+ ligands in both C2 domains of the protein. We conclude that synaptotagmin–SNARE interactions regulate membrane fusion and that cooperation between synaptotagmin's C2 domains is crucial to its function.

Position of Synaptotagmin I at the Membrane Interface:  Cooperative Interactions of Tandem C2 Domains†

Biochemistry ◽  
2006 ◽  
Vol 45 (32) ◽  
pp. 9668-9674 ◽  
Author(s):  
Dawn Z. Herrick ◽  
Stephenie Sterbling ◽  
Katie A. Rasch ◽  
Anne Hinderliter ◽  
David S. Cafiso
Keyword(s):  
Membrane Interface ◽  
C2 Domains ◽  
Cooperative Interactions ◽  
Synaptotagmin I

scholarly journals Lipid Targeting of Synaptotagmin I C2 Domains on Asymmetric Two-Phase Planar Bilayers

2010 ◽  
Vol 98 (3) ◽  
pp. 483a
Author(s):  
Chen Wan ◽  
Volker Kiessling ◽  
Lukas K. Tamm
Keyword(s):  
Two Phase ◽  
Planar Bilayers ◽  
C2 Domains ◽  
Synaptotagmin I

Roles of calcium ions in the membrane binding of C2 domains

2001 ◽  
Vol 359 (3) ◽  
pp. 679-685 ◽  
Author(s):  
Robert V. STAHELIN ◽  
Wonhwa CHO
Keyword(s):  
Conformational Changes ◽  
Membrane Trafficking ◽  
Electrostatic Interactions ◽  
Membrane Binding ◽  
The Other ◽  
Lipid Monolayer ◽  
Dependent Manner ◽  
C2 Domain ◽  
Membrane Penetration ◽  
C2 Domains

The C2 domain is a membrane-targeting domain found in many cellular proteins involved in signal transduction or membrane trafficking. The majority of C2 domains co-ordinate multiple Ca2+ ions and bind the membrane in a Ca2+-dependent manner. To understand the mechanisms by which Ca2+ mediates the membrane binding of C2 domains, we measured the membrane binding of the C2 domains of group IV cytosolic phospholipase A2 (cPLA2) and protein kinase C-α (PKC-α) by surface plasmon resonance and lipid monolayer analyses. Ca2+ ions mainly slow the membrane dissociation of cPLA2-C2, while modulating both membrane association and dissociation rates for PKC-α-C2. Further studies with selected mutants showed that for cPLA2 a Ca2+ ion bound to the C2 domain of cPLA2 induces the intra-domain conformational change that leads to the membrane penetration of the C2 domain whereas the other Ca2+ is not directly involved in membrane binding. For PKC-α, a Ca2+ ion induces the inter-domain conformational changes of the protein and the membrane penetration of non-C2 residues. The other Ca2+ ion of PKC-α-C2 is involved in more complex interactions with the membrane, including both non-specific and specific electrostatic interactions. Together, these studies of isolated C2 domains and their parent proteins allow for the determination of the distinct and specific roles of each Ca2+ ion bound to different C2 domains.

scholarly journals Partitioning of Synaptotagmin I C2 Domains between Liquid-Ordered and Liquid-Disordered Inner Leaflet Lipid Phases

Biochemistry ◽  
2011 ◽  
Vol 50 (13) ◽  
pp. 2478-2485 ◽  
Author(s):  
Chen Wan ◽  
Volker Kiessling ◽  
David S. Cafiso ◽  
Lukas K. Tamm
Keyword(s):  
C2 Domains ◽  
Synaptotagmin I ◽  
Liquid Ordered

scholarly journals Pull-down combined with proteomic strategy reveals functional diversity of synaptotagmin I

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2973
Author(s):  
Tianyao Guo ◽  
Zhigui Duan ◽  
Jia Chen ◽  
Chunliang Xie ◽  
Ying Wang ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Functional Diversity ◽  
Membrane Trafficking ◽  
Metabolic Regulation ◽  
C2 Domains ◽  
Cellular Processes ◽  
Functional Regions ◽  
Synaptotagmin I ◽  
Vesicular Membrane ◽  
The Brain

Synaptotagmin I (Syt I) is most abundant in the brain and is involved in multiple cellular processes. Its two C2 domains, C2A and C2B, are the main functional regions. Our present study employed a pull-down combined with proteomic strategy to identify the C2 domain-interacting proteins to comprehensively understand the biological roles of the C2 domains and thus the functional diversity of Syt I. A total of 135 non-redundant proteins interacting with the C2 domains of Syt I were identified. Out of them, 32 and 64 proteins only bound to C2A or C2B domains, respectively, and 39 proteins bound to both of them. Compared with C2A, C2B could bind to many more proteins particularly those involved in synaptic transmission and metabolic regulation. Functional analysis indicated that Syt I may exert impacts by interacting with other proteins on multiple cellular processes, including vesicular membrane trafficking, synaptic transmission, metabolic regulation, catalysis, transmembrane transport and structure formation, etc. These results demonstrate that the functional diversity of Syt I is higher than previously expected, that its two domains may mediate the same and different cellular processes cooperatively or independently, and that C2B domain may play even more important roles than C2A in the functioning of Syt I. This work not only further deepened our understanding of the functional diversity of Syt I and the functional differences between its two C2 domains, but also provided important clues for the further related researches.

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