*4.4. ATG Analyses*

All ATG triplets within the 5′ UTRs of human ABCA genes were found and highlighted in text editor files (MS Word). The positions (relative to the sATGs as well as TSSs) and flanking sequence contexts were recorded. A scale of four categories was applied for the comparison of flanking sequence contexts: (1) weak (NNN(C/U)NNAUG(A/C/U), any sequence lacking both key nucleotides); (2) adequate (NNN(A/G)NNAUG(A/C/U) or NNN(C/U)NNAUGG, only one of these nucleotides is present); (3) strong (NNN(A/G)NNAUGG, only the two important nucleotides are present); and (4) optimal (GCC(A/G)CCAUGG). The scoring system was adopted from Hernandez et al. [55]. A TIS (translation initiation start) score generated by the NetStart prediction server (DTU Health Tech; https://services.healthtech.dtu.dk/service.php?NetStart-1.0) was also recorded for each ATG analyzed. The scores are in the range [0.0, 1.0]; when greater than 0.5 they represent a probable translation start. Based on this definition we further subdivided the TIS scores into three levels: (1) low (less than 0.1), (2) middle (0.1 to 0.5), and (3) high (greater than 0.5). We proposed a scale of six categories for the evaluation of ATG conservation statuses: 0) found only in humans, (1) conserved in primates, (2) in primates and rodents, (3) in primates, rodents and other placental mammals, (4) in placental mammals and reptiles and birds, (5) in placental mammals, reptiles and birds, and coelacanth or ray-finned fishes.
