Ribosome-inactivating protein

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Ribosome-inactivating protein
SCOP2
1paf / SCOPe / SUPFAM
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
PDBPDB: 1abr​ PDB: 1aha​ PDB: 1ahb​ PDB: 1ahc​ PDB: 1apa​ PDB: 1apg​ PDB: 1br5​ PDB: 1br6​ PDB: 1bry​ PDB: 1cf5​

A ribosome-inactivating protein (RIP) is a

rRNA.[3][4][5] RIPs exist in bacteria and plants.[6]

Members of the family include

T cells and macrophages.[7] Elucidation of the structure-function relationships of RIPs has therefore become a major research effort. It is now known that RIPs are structurally related. A conserved glutamic residue has been implicated in the catalytic mechanism;[8] this lies near a conserved arginine, which also plays a role in catalysis.[9]

Only a minority of RIPs are toxic to humans when consumed, and proteins of this family are found in the vast majority of plants used for human consumption, such as Rice, Maize and Barley. In plants, they are thought to defend against pathogens and insects.[10]

Ribosome-inactivating proteins (RIPs) are separated into the following types based on protein domain composition:[11]

  • Type I (A): RIPs-I are polypeptides composed of an A domain. This is the site of N-glycosidase activity.
  • Type II (AB): RIPs-II are composed of an A domain with similar catalytic activity to Type I RIPs, and a B domain with carbohydrate-binding (lectin) properties. The B domain is able to bind galactosyl moieties on the cell surface which facilitates entry into the cell, thus making Type II particularly cytotoxic. The A and B domains are fused together by disulfide bonds.[11][12] This group excludes bacterial AB5 toxins such as Shiga toxin, as the carbohydrate-binding ability evolved separately and these toxins are more similar to type I RIPs.[11]
  • Type III: RIPs-III are separated into two subgroups. One subgroup (AC) contains the same original RIP domain (A), and a C-terminal with unknown functionality. The other subgroup (AD) is similar to Type I, but contains a site for inactivation.[11]

Examples include:

References

  1. PMID 8411176
    .
  2. ^ Ribosome+Inactivating+Proteins at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
  3. PMID 3276522
    .
  4. PMID 2714255
    .
  5. PMID 1742358
    .
  6. PMID 17855394
    .
  7. S2CID 21524411
    .
  8. PMID 3357883
    .
  9. PMID 8411176
    .
  10. PMID 29479367
    .
  11. ^
    S2CID 9814488
    .
  12. PMID 25496503
    .
  13. PMID 26712000
    .
  14. PMID 25635465
    .


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