Some consider inteins to be selfish DNA8xPietrokovski, S. Protein Sci. 1998; 7: 64–71Crossref | PubMedSee all References, 16xPerler, F.B., Olsen, G.J., and Adam, E. Nucleic Acids Res. 1997; 25: 1087–1093Crossref | PubMed | Scopus (154)See all References, 22xBelfort, M., Reaban, M.E., Coetzee, T., and Dalgaard, J.Z. J. Bacteriol. 1995; 177: 3897–3903PubMedSee all References, 26xHickey, D.A. Trends Genet. 1994; 10: 147–149Abstract | Full Text PDF | PubMed | Scopus (6)See all References, 27xNeff, N.F. Curr. Opin. Cell Biol. 1993; 5: 971–976Crossref | PubMedSee all References, whereas others have suggested that inteins control extein expression2xWu, H., Hu, Z., and Liu, X.Q. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 9226–9231Crossref | PubMed | Scopus (217)See all References, 6xShao, Y. and Kent, S.B.H. Chem. Biol. 1997; 4: 187–194Abstract | Full Text PDF | PubMedSee all References, 22xBelfort, M., Reaban, M.E., Coetzee, T., and Dalgaard, J.Z. J. Bacteriol. 1995; 177: 3897–3903PubMedSee all References. Attempts to demonstrate that inteins have a regulatory function have been hampered, however: splicing of natural precursors in the native host is so rapid that precursor protein is undetectable, and no growth conditions that modulate this process in the native organism have been found. The absence of controllable splicing in natural hosts, the ability of inteins to be mobile genetic elements, and the nature of the protein-splicing self-catalytic mechanism suggest that inteins are simply infectious agents that invade genes with little penalty or reward for the host.I can imagine, however, two possible selective advantages of protein trans-splicing – given the natural example of the Synechocystis sp. PCC6803 dnaE gene1xGorbalenya, A.E. Nucleic Acids Res. 1998; 26: 1741–1748Crossref | PubMed | Scopus (41)See all References, 2xWu, H., Hu, Z., and Liu, X.Q. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 9226–9231Crossref | PubMed | Scopus (217)See all References and the observation that trans-splicing of overlapping intein fragments can occur12xSouthworth, M.W. et al. EMBO J. 1998; 17: 918–926Crossref | PubMed | Scopus (106)See all References12.(1) Trans-splicing might generate new enzyme combinations by ligating one domain to multiple domains. This has the selective advantage of eliminating the possibility of deleterious recombination between proteins that share a common domain. However, to date, no other partial intein/extein gene has been identified in the Synechocystis sp. PCC6803 genome1xGorbalenya, A.E. Nucleic Acids Res. 1998; 26: 1741–1748Crossref | PubMed | Scopus (41)See all