The map of human mtDNA. The orientation is according to the revised Cambridge Reference Sequence (rCRS, GenBank NC_012920.1). Black bent arrows designate origins and direction of new H-strand (OH) and L-strand (OL) synthesis during replication (or, conversely, origins of L-strand and H-strand replication), respectively. Red bent arrows designate mitochondrial promoters that transcribe either H-strand (HSP1 and HSP2) or L-strand (LSP), respectively. Brown arrows: MT-ND1-MT-ND6, NADH dehydrogenase subunits 1 through 6. Blue arrows: MTCO1-MTCO3, cytochrome oxidase subunits 1 through 3. Black arrows: MTATP6 and MT-ATP8, subunits 6 and 8 of the mitochondrial ATPase, Red arrow: MT-CYB, cytochrome b. tRNAs are designated by green letters using single-letter codes for corresponding amino acids.