Figure 4.

Population variation in human IGFBPs 4–6. A, diagram of the human IGFBP4 precursor, including the 21-residue SP and mature 237-amino acid (AA) IGFBP4. The overall population prevalence of variant alleles for each part of the molecule is listed below the map, and the location of the most common variant is depicted in single-letter amino acid code. B, diagram of the human IGFBP5 precursor, including the 20-residue SP and mature 252-amino acid IGFBP5. The overall population prevalence of variant alleles for each part of the molecule is listed below the map, and the location of the most common amino acid variant is depicted in single-letter code. C, diagram of the human IGFBP6 precursor, including the 24-residue SP and mature 216-amino acid IGFBP6. The overall population prevalence of variant alleles for each part of the molecule is listed below the map, and the location of the two most common individual variants is depicted in single-letter amino acid code. The scale bar in A–C represents 20 amino acids. Protein segments for all three IGFBPs include NH₂-terminal, linker, and COOH-terminal domains.