Figure 2.

Proposed models of mammalian mtDNA replication. Two alternative mechanisms of strand-asynchronous replication have been proposed: (A) the bootlace mechanism that relies on mature transcripts. (B) The strand-displacement model that depends on protein (mtSSB) to coat the displaced lagging-strand template. (C) Models A and B can be merged into one in which transcripts are hybridized to the lagging strand template with mtSSB occupying any gaps between RNAs. Ori-H—origin of heavy-strand DNA replication.