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Endonuclease domain encoded by various R1- and I-clade non-long terminal repeat retrotransposons This family contains the endonuclease (EN) domain of various non-long terminal repeat (non-LTR) retrotransposons, long interspersed nuclear elements (LINEs) which belong to the subtype 2, R1- and I-clade. LINES can be classified into two subtypes. Subtype 2 has two ORFs: the second (ORF2) encodes a modular protein consisting of an N-terminal apurine/apyrimidine endonuclease domain (EN), a central reverse transcriptase, and a zinc-finger-like domain at the C-terminus. Most non-LTR retrotransposons are inserted throughout the host genome; however, many retrotransposons of the R1 clade exhibit target-specific retrotransposition. This family includes the endonucleases of SART1 and R1bm, from the silkworm Bombyx mori, which belong to the R1-clade. It also includes the endonuclease of snail (Biomphalaria glabrata) Nimbus/Bgl and mosquito Aedes aegypti (MosquI), both which belong to the I-clade. This family belongs to the large EEP (exonuclease/endonuclease/phosphatase) superfamily that contains functionally diverse enzymes that share a common catalytic mechanism of cleaving phosphodiester bonds. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",