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9  structures 425  species 1  interaction 1633  sequences 15  architectures

Family: Syntaxin (PF00804)

Summary: Syntaxin

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This is the Wikipedia entry entitled "Syntaxin". More...

Syntaxin Edit Wikipedia article

PDB 1br0 EBI.jpg
Structure of an evolutionarily conserved N-terminal domain of syntaxin 1A.[1]
Symbol Syntaxin
Pfam PF00804
InterPro IPR006011
SCOP 1br0
OPM superfamily 218
OPM protein 3hd7

Syntaxins are a family of membrane integrated Q-SNARE proteins participating in exocytosis.[2]


Syntaxins possess a single C-terminal transmembrane domain, a SNARE domain (known as H3), and an N-terminal regulatory domain (Habc). Syntaxin 17 may have two transmembrane domains.

  • The SNARE (H3) domain binds to both synaptobrevin and SNAP-25 forming the core SNARE complex. Formation of this incredibly stable SNARE core complex is believed to generate the free energy required to initiate fusion between the vesicle membrane and plasma membrane.
  • The N-terminal Habc domain is formed by 3 \alpha-helices and when collapsed onto its own H3 helix forms an inactive "closed" syntaxin conformation. This closed conformation of syntaxin is believed to be stabilized by binding of Munc-18 (nSec1), although more recent data suggests that nSec1 may bind to other conformations of syntaxin, as well. The "open" syntaxin conformation is the conformation that is competent to form into SNARE core complexes.


Molecular machinery driving exocytosis in neuromediator release. The core SNARE complex is formed by four \alpha-helices contributed by synaptobrevin, syntaxin and SNAP-25, synaptotagmin serves as a Ca^{2+} sensor and regulates intimately the SNARE zipping.[3]

In vitro syntaxin per se is sufficient to drive spontaneous calcium independent fusion of synaptic vesicles containing v-SNAREs.[4]

More recent and somewhat controversial amperometric data suggest that the transmembrane domain of Syntaxin1A may form part of the fusion pore of exocytosis.[5]


Syntaxins bind synaptotagmin in a calcium-dependent fashion and interact with voltage dependent calcium and potassium channels via the C-terminal H3 domain. Direct syntaxin-channel interaction is a suitable molecular mechanism for proximity between the fusion machinery and the gates of Ca^{2+} entry during depolarization of the presynaptic axonal boutons.

The Sec1/Munc18 protein family is known to bind to Syntaxin and regulate Syntaxins machinery. Munc18-1 binds to Syntaxin 1A via two distinct sites referred as N-terminus binding and "closed" conformation that incorporates both the central Habc domain and the SNARE core domain. Munc18-1 binding to the N-terminus of Syntaxin-1 is thought to facilitate Syntaxin-1 interaction with another SNARE, while binding to the "closed" conformation of Syntaxin-1 is believed to be inhibitory.

Recently published data show that alternative spliced Syntaxin 1 (STX1B) which lacks the transmembrane domain localizes in the nuclei.[6]


Human genes encoding syntaxin proteins include:

STX10, STX11, STX12, STX16, STX17, STX18, STX19

Examples of Syntaxin

Syntaxin 6

References and notes

  1. ^ Fernandez I, Ubach J, Dulubova I, Zhang X, Südhof TC, Rizo J (September 1998). "Three-dimensional structure of an evolutionarily conserved N-terminal domain of syntaxin 1A". Cell 94 (6): 841–9. doi:10.1016/S0092-8674(00)81742-0. PMID 9753330. 
  2. ^ Bennett MK, García-Arrarás JE, Elferink LA, Peterson K, Fleming AM, Hazuka CD, Scheller RH (September 1993). "The syntaxin family of vesicular transport receptors". Cell 74 (5): 863–73. doi:10.1016/0092-8674(93)90466-4. PMID 7690687. 
  3. ^ Georgiev, Danko D .; James F . Glazebrook (2007). "Subneuronal processing of information by solitary waves and stochastic processes". In Lyshevski, Sergey Edward. Nano and Molecular Electronics Handbook. Nano and Microengineering Series. CRC Press. pp. 17–1–17–41. ISBN 978-0-8493-8528-5. 
  4. ^ Woodbury DJ, Rognlien K (2000). "The t-SNARE syntaxin is sufficient for spontaneous fusion of synaptic vesicles to planar membranes". Cell Biol. Int. 24 (11): 809–18. doi:10.1006/cbir.2000.0631. PMID 11067766. 
  5. ^ Han X, Wang CT, Bai J, Chapman ER, Jackson MB (April 2004). "Transmembrane segments of syntaxin line the fusion pore of Ca2+-triggered exocytosis". Science 304 (5668): 289–92. doi:10.1126/science.1095801. PMID 15016962. 
  6. ^ Pereira S, Massacrier A, Roll P, Vérine A, Etienne-Grimaldi MC, Poitelon Y, Robaglia-Schlupp A, Jamali S, Roeckel-Trevisiol N, Royer B, Pontarotti P, Lévêque C, Seagar M, Lévy N, Cau P, Szepetowski P (November 2008). "Nuclear localization of a novel human syntaxin 1B isoform". Gene 423 (2): 160–71. doi:10.1016/j.gene.2008.07.010. PMID 18691641. 

External links

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

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Syntaxins are the prototype family of SNARE proteins. They usually consist of three main regions - a C-terminal transmembrane region, a central SNARE domain which is characteristic of and conserved in all syntaxins (PF05739), and an N-terminal domain that is featured in this entry. This domain varies between syntaxin isoforms; in syntaxin 1A (O35526) it is found as three alpha-helices with a left-handed twist. It may fold back on the SNARE domain to allow the molecule to adopt a 'closed' configuration that prevents formation of the core fusion complex - it thus has an auto-inhibitory role. The function of syntaxins is determined by their localisation. They are involved in neuronal exocytosis, ER-Golgi transport and Golgi-endosome transport, for example. They also interact with other proteins as well as those involved in SNARE complexes. These include vesicle coat proteins, Rab GTPases, and tethering factors [6].

Literature references

  1. Jantti J, Aalto MK, Oyen M, Sundqvist L, Keranen S, Ronne H; , J Cell Sci 2002;115:409-420.: Characterization of temperature-sensitive mutations in the yeast syntaxin 1 homologues Sso1p and Sso2p, and evidence of a distinct function for Sso1p in sporulation. PUBMED:11839791 EPMC:11839791

  2. Marash M, Gerst JE; , EMBO J 2001;20:411-421.: t-SNARE dephosphorylation promotes SNARE assembly and exocytosis in yeast. PUBMED:11157748 EPMC:11157748

  3. Dulubova I, Yamaguchi T, Wang Y, Sudhof TC, Rizo J; , Nat Struct Biol 2001;8:258-264.: Vam3p structure reveals conserved and divergent properties of syntaxins. PUBMED:11224573 EPMC:11224573

  4. Carr CM; , Nat Struct Biol 2001;8:186-188.: The taming of the SNARE. PUBMED:11224554 EPMC:11224554

  5. Namy O, Hatin I, Stahl G, Liu H, Barnay S, Bidou L, Rousset JP; , Genetics 2002;161:585-594.: Gene overexpression as a tool for identifying new trans-acting factors involved in translation termination in Saccharomyces cerevisiae. PUBMED:12072456 EPMC:12072456

  6. Teng FY, Wang Y, Tang BL; , Genome Biol 2001;2:REVIEWS3012.: The syntaxins. PUBMED:11737951 EPMC:11737951

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR006011

Syntaxins A and B are nervous system-specific proteins implicated in the docking of synaptic vesicles with the presynaptic plasma membrane. Syntaxins are a family of receptors for intracellular transport vesicles. Each target membrane may be identified by a specific member of the syntaxin family [PUBMED:7690687]. Members of the syntaxin family [PUBMED:8493722, PUBMED:8490959] have a size ranging from 30 Kd to 40 Kd; a C-terminal extremity which is highly hydrophobic and anchors the protein on the cytoplasmic surface of cellular membranes; a central, well conserved region, which seems to be in a coiled-coil conformation.

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan SNARE-fusion (CL0445), which has the following description:

The SNARE-fusion complex families are characterised by being tetrameric coiled-coil structures.

The clan contains the following 4 members:

SNARE Synaptobrevin Syntaxin Syntaxin_2


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Curation and family details

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Seed source: Pfam-B_1158 (release 2.1)
Previous IDs: none
Type: Domain
Author: Bateman A
Number in seed: 171
Number in full: 1633
Average length of the domain: 101.60 aa
Average identity of full alignment: 21 %
Average coverage of the sequence by the domain: 33.55 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.0 25.0
Trusted cut-off 25.0 25.0
Noise cut-off 24.9 24.9
Model length: 103
Family (HMM) version: 20
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Species distribution

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There is 1 interaction for this family. More...



For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Syntaxin domain has been found. There are 9 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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