Summary: Sad1 / UNC-like C-terminal
This is the Wikipedia entry entitled "SUN domain". More...
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SUN domain Edit Wikipedia article
SUN (Sad1p, UNC-84) domains are conserved C-terminal protein regions a few hundred amino acids long. SUN domains are usually found following a transmembrane domain and a less conserved region of amino acids. Most proteins containing SUN domains are thought to be involved in the positioning of the nucleus in the cell. It is thought that SUN domains interact directly with KASH domains in the space between the outer and inner nuclear membranes to bridge the nuclear envelope and transfer force from the nucleoskeleton to the cytoplasmic cytoskeleton which enables mechanosensory roles in cells. SUN proteins are thought to localize to the inner nuclear membrane. The S. pombe Sad1 protein localises at the spindle pole body. In mammals, the SUN domain is present in two proteins, Sun1 and Sun2. The SUN domain of Sun2 has been demonstrated to be in the periplasm.
Examples of SUN Proteins
- SUN1, 2, and 3
- SUN1, 2, 3, 4, and 5
- SUN1, and 2
- Uzer et al.(2015) "Cell mechanosensitivity to extremely low magnitude signals is enabled by a LINCed nucleus" Stem Cells,doi: 10.1002/stem.2004 PMID 25787126
- Tzur YB, Wilson KL, Gruenbaum Y (Oct 2006). "SUN-domain proteins: 'Velcro' that links the nucleoskeleton to the cytoskeleton". Nat Rev Mol Cell Biol. 7 (10): 782–8. doi:10.1038/nrm2003. PMID 16926857.
- Hodzic DM, Yeater DB, Bengtsson L, Otto H, Stahl PD (June 2004). "Sun2 is a novel mammalian inner nuclear membrane protein". J. Biol. Chem. 279 (24): 25805–12. doi:10.1074/jbc.M313157200. PMID 15082709.
- Raff JW (September 1999). "The missing (L) UNC?". Curr. Biol. 9 (18): R708–10. doi:10.1016/S0960-9822(99)80446-1. PMID 10508607.
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Sad1 / UNC-like C-terminal Provide feedback
The C. elegans UNC-84 protein is a nuclear envelope protein that is involved in nuclear anchoring and migration during development. The S. pombe Sad1 protein localises at the spindle pole body. UNC-84 and and Sad1 share a common C-terminal region, that is often termed the SUN (Sad1 and UNC) domain [1-2]. In mammals, the SUN domain is present in two proteins, Sun1 and Sun2 . The SUN domain of Sun2 has been demonstrated to be in the periplasm .
This tab holds annotation information from the InterPro database.
InterPro entry IPR012919
Sad1/UNC-84 (SUN)-domain proteins are inner nuclear membrane (INM) proteins that are part of bridging complexes linking cytoskeletal elements with the nucleoskeleton. Originaly identified based on an ~150-amino acid region of homology between the C terminus of the Schizosaccharomyces pombe Sad1 protein and the Caenorhabditis elegans UNC-84 protein, SUN proteins are present in the proteomes of most eucaryotes. In addition to the SUN domain, these proteins contain a transmembrane sequence and at least one coiled-coil domain and localise to the inner nuclear envelope. SUN proteins are anchored in the inner nuclear envelope by their transmembrane segment and oriented in the membrane such that the C-terminal SUN domain is located in the space between the inner and outer nuclear membrane. Here, the SUN domain can interact with the C- terminal tail of an outer nuclear envelope protein that binds to the cytoskeleton, including the centrosome [PUBMED:15611647, PUBMED:16923827, PUBMED:19807882].
Some proteins known to contain a SUN domain are listed below:
- Fission yeast spindle pole body-associated protein Sad1.
- Yeast spindle pole body assembly component MPS3, essential for nuclear division and fusion.
- Yeast uncharacterised protein SLP1.
- Caenorhabditis nuclear migration and anchoring protein UNC-84.
- Caenorhabditis SUN domain-containing protein 1 (sun-1), involved in centrosome attachment to the nucleus.
- Mammalian sperm-associated antigen 4 protein (SPAG4), may assist the organisation and assembly of outer dense fibres (ODFs), a specific structure of the sperm tail.
- Mammalian sperm-associated antigen 4-like protein (SPAG4L).
- Mammalian SUN1.
- Mammalian SUN2.
- Mammalian SUN3.
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
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This large superfamily contains beta sandwich domains with a jelly roll topology. Many of these families are involved in carbohydrate recognition. Despite sharing little sequence similarity they do share a weak sequence motif, with a conserved bulge in the C-terminal beta sheet. The probable role of this bulge is in bending of the beta sheet that contains the bulge. This enables the curvature of the sheet forming the sugar binding site .
The clan contains the following 32 members:Allantoicase ANAPC10 Bac_rhamnosid_N BetaGal_dom4_5 CBM-like CBM27 CBM60 CBM_11 CBM_15 CBM_17_28 CBM_35 CBM_4_9 CBM_6 CIA30 DUF5000 DUF642 Endotoxin_C Ephrin_lbd F5_F8_type_C FBA Glyco_hydro_2_N Laminin_N Lyase_N Muskelin_N NPCBM P_proprotein PA-IL PepX_C PITH PPC Sad1_UNC XRCC1_N
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the UniProtKB sequence database using the family HMM
- alignment generated by searching the NCBI sequence database using the family HMM
- alignment generated by searching the metagenomics sequence database using the family HMM
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
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Curation and family details
|Seed source:||Pfam-B_5052 (release 14.0)|
|Author:||Wood V, Finn RD|
|Number in seed:||25|
|Number in full:||1475|
|Average length of the domain:||123.50 aa|
|Average identity of full alignment:||23 %|
|Average coverage of the sequence by the domain:||15.40 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 11927849 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||10|
|Download:||download the raw HMM for this family|
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There is 1 interaction for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
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 Sad1_UNC domain has been found. There are 5 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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