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10  structures 219  species 2  interactions 11334  sequences 438  architectures

Family: SRCR (PF00530)

Summary: Scavenger receptor cysteine-rich domain

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This is the Wikipedia entry entitled "Scavenger receptor cysteine-rich protein domain". More...

Scavenger receptor cysteine-rich protein domain Edit Wikipedia article

PDB 1by2 EBI.jpg
structure of m2bp scavenger receptor cysteine-rich domain
Symbol SRCR
Pfam PF00530
InterPro IPR001190
SCOP 1by2

In molecular biology, the protein domain SRCR is short for Scavenger receptor cysteine-rich domain. They are found solely in eukaryotes. These domains are present on the cell membrane and have a role in binding to specific ligands and are often found to be involved with the immune system.[1]


The function of these endocytic receptors are to mediating non-opsonic phagocytosis in response to foreign ligands. This triggers various processes of host defence and immune response.[2]


The structure contains a six stranded beta-sheet and one alpha-helix.[1]


The speract receptor found in egg, is a transmembrane glycoprotein.[3] Other members of this family include the macrophage scavenger receptor type I (a membrane glycoprotein implicated in the pathologic deposition of cholesterol in arterial walls during artherogenesis), an enteropeptidase and T-cell surface glycoprotein CD5 (may act as a receptor in regulating T-cell proliferation).


  1. ^ a b Hohenester E, Sasaki T, Timpl R (1999). "Crystal structure of a scavenger receptor cysteine-rich domain sheds light on an ancient superfamily.". Nat Struct Biol 6 (3): 228–32. doi:10.1038/6669. PMID 10074941. 
  2. ^ Liu L, Yang J, Qiu L, Wang L, Zhang H, Wang M et al. (2011). "A novel scavenger receptor-cysteine-rich (SRCR) domain containing scavenger receptor identified from mollusk mediated PAMP recognition and binding.". Dev Comp Immunol 35 (2): 227–39. doi:10.1016/j.dci.2010.09.010. PMID 20888856. 
  3. ^ Resnick D, Pearson A, Krieger M (January 1994). "The SRCR superfamily: a family reminiscent of the Ig superfamily". Trends Biochem. Sci. 19 (1): 5–8. doi:10.1016/0968-0004(94)90165-1. PMID 8140623. 

This article incorporates text from the public domain Pfam and InterPro IPR001190

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.

Scavenger receptor cysteine-rich domain Provide feedback

These domains are disulphide rich extracellular domains. These domains are found in several extracellular receptors and may be involved in protein-protein interactions.

Literature references

  1. Resnick D, Pearson A, Krieger M; , Trends Biochem Sci 1994;19:5-8.: The SRCR superfamily - A family reminiscent of the Ig superfamily. PUBMED:8140623 EPMC:8140623

  2. Hohenester E, Sasaki T, Timpl R; , Nat Struct Biol 1999;6:228-232.: Crystal structure of a scavenger receptor cysteine-rich domain sheds light on an ancient superfamily. PUBMED:10074941 EPMC:10074941

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR001190

The scavenger receptor cysteine-rich (SRCR) domain is an ancient and highly conserved domain of about 110 residues which is found in diverse secreted and cell-surface proteins, like the type I scavenger receptor, the speract receptor, CD5/Ly-1, CD6, or complement factor I [PUBMED:1978939]. Tandem repeats of SRCR domains are common in the membrane bound proteins. Most SRCR domains have six to eight cysteines that participate in intradomain disulfide bonds. SRCR domains have been subdivided into two groups, A and B, primarily on the differences in the spacing pattern between the cysteine residues [PUBMED:8140623, PUBMED:10074941].

Although the biochemical functions of SRCR domains have not been established with certainty, they are likely to mediate protein-protein interactions and ligand binding [PUBMED:8140623, PUBMED:10074941].

Determination of the crystal structure of the SRCR domain of M2BP reveals that the M2NP SRCR adopts a compact fold of approximate dimensions 22 x 26 x 30 Angstrom, organised around a curved six-stranded beta-sheet cradling an alpha- helix [PUBMED:10074941].

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 SRCR (CL0550), which has the following description:

The clan contains the following 3 members:



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 using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics sequence database. More...

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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.

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HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

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Seed source: Reference [1]
Previous IDs: none
Type: Domain
Author: Bateman A
Number in seed: 81
Number in full: 11334
Average length of the domain: 96.30 aa
Average identity of full alignment: 34 %
Average coverage of the sequence by the domain: 45.14 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 80369284 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 26.1 26.1
Trusted cut-off 26.1 26.1
Noise cut-off 26.0 26.0
Model length: 100
Family (HMM) version: 14
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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There are 2 interactions for this family. More...

Ldl_recept_a SRCR


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 SRCR domain has been found. There are 10 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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