EVOLUTION OF THE MAMMALIAN MITOCHONDRIAL CONTROL REGION - COMPARISONSOF CONTROL REGION SEQUENCES BETWEEN MONOTREME AND THERIAN MAMMALS

The platypus mitochondrial control legion has been cloned and sequence d. Comparative analysis of this sequence with the published control re gion sequences of several other mammalian species has identified regio ns of sequence consensus that are conserved throughout the Mammalia. R egions predicted to form thermodynamically stable secondary structures in the platypus are also homologous to such putative structures in ot her species. In addition to these conserved structures, the platypus m itochondrial control region also contains a number of unusual features , including two regions of-repetitive sequence, one of which gives ris e to pronounced length variation between animals. Possible functions f or the conserved structures and a mechanism for the generation of the control region length variation are proposed with respect to our curre nt understanding of mitochondrial replication and transcription.