What is "intein"

n. (context biochemistry English) A segment of a protein, analogous to an intron, that is able to excise itself, the gap being closed with a peptide bond

thumb|upright=1.25|alt=mechanism of protein splicing involving inteins|The mechanism of protein splicing involving inteins. In this scheme, the N-extein is shown in red, the intein in black, and the C-extein in blue. X represents either an oxygen or sulfur atom. An intein is a segment of a protein that is able to excise itself and join the remaining portions (the exteins) with a peptide bond in a process termed protein splicing. Inteins have also been called "protein introns".

Intein-mediated protein splicing occurs after the intein-containing mRNA has been translated into a protein. This precursor protein contains three segments—an N-extein followed by the intein followed by a C-extein. After splicing has taken place, the resulting protein contains the N-extein linked to the C-extein; this splicing product is also termed an extein.