Intein (IPR006142)

Short name: INTEIN

Overlapping homologous superfamilies

Domain relationships



Inteins, or protein introns, are parts of protein sequences that are post-translationally excised, their flanking regions (exteins) being spliced together to yield an additional protein product [PMID: 7756989,PMID: 8165123]. This process is believed to be self-catalysed, apparently initiating at the C-terminal splice junction, where a conserved asparagine residue mediates the nucleophilic attack of the peptide bond between it and its neighbouring residue. Most inteins consist of two domains: One is involved in autocatalytic splicing, and the other is an endonuclease that is important in the spread of inteins [PMID: 12142479].

Inteins are between 134 and 608 amino acids long, and they are found in members of all three domains of life: eukaryotes, bacteria, and archaea, although most frequently in archaea. Inteins are found in proteins with diverse functions, including metabolic enzymes, DNA and RNA polymerases, proteases, ribonucleotide reductases, and the vacuolar-type ATPase. However, enzymes involved in DNA replication and repair appear to dominate. Inteins are found in conserved regions of conserved proteins and can be regarded as parasitic genetic elements [PMID: 12142479]. Inteins are difficult to identify from sequence data because they lie in the same reading frame as the spliced protein and they are characterised by only a few short conserved motifs [PMID: 7756989]: two of these are similar to the nonapeptide LAGLIDADG, which is diagnostic of certain homing endonucleases (mutation of one such motif causes loss of endonucleic activity, but not of the protein splicing function); another includes the C' splice site, mutations in which disable protein function.

GO terms

Biological Process

GO:0016539 intein-mediated protein splicing

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.