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Fig. 16 | BMC Evolutionary Biology

Fig. 16

From: From molecular to cellular form: modeling the first major transition during the arising of life

Fig. 16

About the tag mechanism involved in the model. Color legends: (grey – template/substrate); (yellow – catalytic domain of REP); (orange – tag); (red – catalytic domain of NSR); (blue – complementary sequence of REP’s catalytic domain); (green – complementary sequence of NSR’s catalytic domain). Note that in a tag mechanism like this, the reverse-tag and the tag-recognizing domain of REP are actually of the same sequence as the tag (orange), which is palindromic. a REP binds onto the template by recognizing a 5′-tag, and when the copying proceeds to the tag segment, the base-pairing between the template’s tag and the REP’s tag-recognizing domain would separate. b A functional REP should contain a catalytic domain and a tag (actually a tag-recognizing domain), whereas a functional NSR needs only to contain its catalytic domain. To be able to spread in the system by replication, both REP and NSR must contain two tags flanking the catalytic domain (actually a 5′-tag and a 3′-reverse-tag)

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