Summary: Calpain large subunit, domain III
Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.
The Pfam group coordinates the annotation of Pfam families in Wikipedia, but we have not yet assigned a Wikipedia article to this family. If you think that a particular Wikipedia article provides good annotation, please let us know.
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.
Calpain large subunit, domain III Provide feedback
The function of the domain III and I are currently unknown. Domain II is a cysteine protease and domain IV is a calcium binding domain. Calpains are believed to participate in intracellular signaling pathways mediated by calcium ions.
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR022682
This group of cysteine peptidases belong to the MEROPS peptidase family C2 (calpain family, clan CA). A type example is calpain, which is an intracellular protease involved in many important cellular functions that are regulated by calcium [PUBMED:2539381,PUBMED:11517928]. The protein is a complex of 2 polypeptide chains (light and heavy), with eleven known active peptidases in humans and two non-peptidase homologues known as calpamodulin and androglobin [PUBMED:21864727]. These include a highly calcium-sensitive (i.e., micro-molar range) form known as mu-calpain, mu-CANP or calpain I; a form sensitive to calcium in the milli-molar range, known as m-calpain, m-CANP or calpain II; and a third form, known as p94, which is found in skeletal muscle only [PUBMED:2555341].
All forms have identical light but different heavy chains. Both mu- and m-calpain are heterodimers containing an identical 28kDa subunit and an 80kDa subunit that shares 55-65% sequence homology between the two proteases [PUBMED:7845226, PUBMED:2539381]. The crystallographic structure of m-calpain reveals six "domains" in the 80kDa subunit [PUBMED:9396712,PUBMED:11328585]:
- A 19-amino acid NH2-terminal sequence;
- Active site domain IIa;
- Active site domain IIb. Domain 2 shows low levels of sequence similarity to papain; although the catalytic His has not been located by biochemical means, it is likely that calpain and papain are related [PUBMED:7845226].
- Domain III;
- An 18-amino acid extended sequence linking domain III to domain IV;
- Domain IV, which resembles the penta EF-hand family of polypeptides, binds calcium and regulates activity [PUBMED:7845226]. Ca2+-binding causes a rearrangement of the protein backbone, the net effect of which is that a Trp side chain, which acts as a wedge between catalytic domains IIa and IIb in the apo state, moves away from the active site cleft allowing for the proper formation of the catalytic triad [PUBMED:11914728].
Calpain-like mRNAs have been identified in other organisms including bacteria, but the molecules encoded by these mRNAs have not been isolated, so little is known about their properties. How calpain activity is regulated in these organisms cells is still unclear In metazoans, the activity of calpain is controlled by a single proteinase inhibitor, calpastatin (INTERPRO). The calpastatin gene can produce eight or more calpastatin polypeptides ranging from 17 to 85 kDa by use of different promoters and alternative splicing events. The physiological significance of these different calpastatins is unclear, although all bind to three different places on the calpain molecule; binding to at least two of the sites is Ca2+ dependent. The calpains ostensibly participate in a variety of cellular processes including remodelling of cytoskeletal/membrane attachments, different signal transduction pathways, and apoptosis. Deregulated calpain activity following loss of Ca2+ homeostasis results in tissue damage in response to events such as myocardial infarcts, stroke, and brain trauma [PUBMED:12843408].
This entry represents domain III. The function of the domain III and I are currently unknown. Domain II is a cysteine protease and domain IV is a calcium binding domain. Calpains are believed to participate in intracellular signaling pathways mediated by calcium ions.
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
- 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
- a link to the page in the Pfam site showing information about the sequence that the graphic describes
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
Note that you can see the family page for a particular domain by clicking on the graphic. You can also choose to see all sequences which have a given architecture by clicking on the Show link in each row.
Finally, because some families can be found in a very large number of architectures, we load only the first fifty architectures by default. If you want to see more architectures, click the button at the bottom of the page to load the next set.
Loading domain graphics...
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 70 members:7TMR-DISMED2 Agarase_CBM Allantoicase ANAPC10 Arabino_trans_C Bac_rhamnosid_N BcsB BetaGal_dom4_5 BPA_C Calpain_III CBM-like CBM27 CBM32 CBM46 CBM60 CBM65_1 CBM_11 CBM_15 CBM_17_28 CBM_26 CBM_35 CBM_4_9 CBM_6 CE2_N CIA30 Clenterotox Cry1Ac_D5 DUF4465 DUF4627 DUF5000 DUF5010_C DUF5077 DUF5625 DUF642 Endotoxin_C Ephrin_lbd Exop_C F5_F8_type_C FBA FlhE GH101_N GH115_C Glft2_N Glyco_hydro_2_N GxDLY HA70_C Laminin_B Laminin_N Lectin_like Lipl32 Lyase_N Malectin Malectin_like Muskelin_N NPCBM P_proprotein PA-IL PAW PCMD PepX_C PINIT PITH PPC PulA_N1 Sad1_UNC SGBP_B_XBD TcA_TcB_BD Thioredoxin_10 XRCC1_N YpM
We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the UniProtKB sequence database, the NCBI sequence database, and our metagenomics sequence database. More...
There are various ways to view or download the sequence alignments that we store. We provide several sequence viewers and a plain-text Stockholm-format file for download.
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
You can see the alignments as HTML or in three different sequence viewers:
- a Java applet developed at the University of Dundee. You will need Java installed before running jalview
- an HTML page showing the whole alignment.Please note: full Pfam alignments can be very large. These HTML views are extremely large and often cause problems for browsers. Please use either jalview or the Pfam viewer if you have trouble viewing the HTML version
- an HTML-based representation of the alignment, coloured according to the posterior-probability (PP) values from the HMM. As for the standard HTML view, heatmap alignments can also be very large and slow to render.
You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
You can also change the order in which sequences are listed in the alignment, change how insertions are represented, alter the characters that are used to represent gaps in sequences and, finally, choose whether to download the alignment or to view it in your browser directly.
You may find that large alignments cause problems for the viewers and the reformatting tool, so we also provide all alignments in Stockholm format. You can download either the plain text alignment, or a gzipped version of it.
We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.