Figure 1. Structural organization of the human apolipoprotein (Apo) A-I, A-II, A-IV, C-I, C-II, C-III and E genes. The wide bars represent the exons and are divided into several regions: the open bars at the two ends represent the 5¢ and 3¢ untranslated regions; the hatched bars, the signal peptide regions; and the solid bars, the mature peptide regions of the respective genes. The numbers above the exons indicate the length (in nucleotides) of the exons.

Figure 2. Internal repeats of the soluble human apolipoproteins. (a) The last 33 amino acids of exon 3 (exon 2 for apoA-IV and apoA-V) can be divided into three repeats of 11 amino acids. Colours indicate amino acid character as follows: purple, helix-breaking proline (P); red, acidic residues aspartate (D) and glutamate (E); blue, basic residues arginine (R) and lysine (K) and green, hydrophobic residues methionine (M), valine (V), leucine (L), isoleucine (I), phenylalanine (F), tyrosine (Y) or tryptophan (W). The remaining amino acids – glycine (G), alanine (A), serine (S), threonine (T), asparagine (N), glutamine (Q), histidine (H) and cysteine (C) – are not coloured and are considered to have indifferent characters. Any column containing four or more amino acids of a single colour is said to possess that character, and the amino acids of that character are boxed. Numbers along the left margin are residue numbers in the mature peptide. (b) Most of the repeats in exon 4 are 22-mers, each of which is made up of two 11-mers, and the other repeats are 11-mers. If more than 18 amino acids in a column are of a single colour, the amino acids with that character are boxed.