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This family of proteins are involved in protein sorting and transport from the endosome to the vacuole/lysosome in eukaryotic cells. Vacuoles/lysosomes play an important role in the degradation of both lipids and cellular proteins. In order to perform this degradative function, vacuoles/lysosomes contain numerous hydrolases which have been transported in the form of inactive precursors via the biosynthetic pathway and are proteolytically activated upon delivery to the vacuole/lysosome. The delivery of transmembrane proteins, such as activated cell surface receptors to the lumen of the vacuole/lysosome, either for degradation/downregulation, or in the case of hydrolases, for proper localisation, requires the formation of multivesicular bodies (MVBs). These late endosomal structures are formed by invaginating and budding of the limiting membrane into the lumen of the compartment. During this process, a subset of the endosomal membrane proteins is sorted into the forming vesicles. Mature MVBs fuse with the vacuole/lysosome, thereby releasing cargo containing vesicles into its hydrolytic lumen for degradation. Endosomal proteins that are not sorted into the intralumenal MVB vesicles are either recycled back to the plasma membrane or Golgi complex, or remain in the limiting membrane of the MVB and are thereby transported to the limiting membrane of the vacuole/lysosome as a consequence of fusion. Therefore, the MVB sorting pathway plays a critical role in the decision between recycling and degradation of membrane proteins . A few archaeal sequences are also present within this family.
Babst M, Katzmann DJ, Estepa-Sabal EJ, Meerloo T, Emr SD; , Dev Cell 2002;3:271-282.: Escrt-III: an endosome-associated heterooligomeric protein complex required for mvb sorting. PUBMED:12194857 EPMC:12194857
Teo H, Perisic O, Gonzalez B, Williams RL; , Dev Cell 2004;7:559-569.: ESCRT-II, an endosome-associated complex required for protein sorting: crystal structure and interactions with ESCRT-III and membranes. PUBMED:15469844 EPMC:15469844
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR005024
This is a family of eukaryotic proteins which are variously described as either hypothetical protein, developmental protein or related to yeast SNF7. The family contains human CHMP1. CHMP1 (CHromatin Modifying Protein; CHarged Multivesicular body Protein), is encoded by an alternative open reading frame in the PRSM1 gene [PUBMED:8863740] and is conserved in both complex and simple eukaryotes. CHMP1 contains a predicted bipartite nuclear localisation signal and distributes as distinct forms to the cytoplasm and the nuclear matrix in all cell lines tested.
Human CHMP1 is strongly implicated in multivesicular body formation. A multivesicular body is a vesicle-filled endosome that targets proteins to the interior of lysosomes. Immunocytochemistry and biochemical fractionation localise CHMP1 to early endosomes and CHMP1 physically interacts with SKD1/VPS4, a highly conserved protein directly linked to multivesicular body sorting in yeast. Similar to the action of a mutant SKD1 protein, over expression of a fusion derivative of human CHMP1 dilates endosomal compartments and disrupts the normal distribution of several endosomal markers. Genetic studies in Saccharomyces cerevisiae (Baker's yeast) further support a conserved role of CHMP1 in vesicle trafficking. Deletion of CHM1, the budding yeast homologue of CHMP1, results in defective sorting of carboxypeptidases S and Y and produces abnormal, multi-lamellar prevacuolar compartments. This phenotype classifies CHM1 as a member of the class E vacuolar protein sorting genes [PUBMED:11559747].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Biological process||protein transport (GO:0015031)|
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Curation and family details
|Seed source:||Pfam-B_1641 (release 6.6)|
|Previous IDs:||DUF279; SNF7; ESCRT-III;|
|Author:||Mifsud W, Moxon SJ, Mistry J, Wood V|
|Number in seed:||33|
|Number in full:||5157|
|Average length of the domain:||169.80 aa|
|Average identity of full alignment:||19 %|
|Average coverage of the sequence by the domain:||69.53 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 80369284 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||17|
|Download:||download the raw HMM for this family|
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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 Snf7 domain has been found. There are 26 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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