The Amino Acid Sequence of Human Plasma Prealbumin

The complete amino acid sequence of plasma prealbumin has been determined. Prealbumin forms a stable complex with plasma retinol-binding protein and plays an important role in vitamin A transport. Prealbumin also binds thyroxine, and is involved in transport of thyroid hormone. The prealbumin molecule is a stable tetramer, composed of 4 identical subunits, with over-all molecular weight of 54,980. Each prealbumin subunit contains 127 amino acids, including 1 cysteine (position 10), 1 methionine (position 13), 4 arginine, and 8 lysine residues. Thirteen tryptic peptides were aligned after studies which included the tryptic digestion of maleylated, reduced, and carboxymethylated prealbumin (to yield 5 peptides), and subsequent tryptic digestion of these peptides after removal of the maleyl groups. The sequence of each subunit is: NH2-Gly-Pro-Thr-Gly-Thr-Gly-Glu-Ser-Lys-Cys-Pro-Leu-Met-Val-Lys-Val-Leu-Asp-Ala-Val-Arg-Gly-Ser-Pro-Ala-Ile-Asn-Val-Ala-Val-His-Val-Phe-Arg-Lys-Ala-Ala-Asp-Asp-Thr-Trp-Glu-Pro-Phe-Ala-Ser-Gly-Lys-Thr-Ser-Glu-Ser-Gly-Glu-Leu-His-Gly-Leu-Thr-Thr-Glx-Glx-Gln-Phe-Val-Glu-Gly-Ile-Tyr-Lys-Val-Glu-Ile-Asp-Thr-Lys-Ser-Tyr-Trp-Lys-Ala-Leu-Gly-Ile-Ser-Pro-Phe-His-Glu-His-Ala-Glu-Val-Val-Phe-Thr-Ala-Asn-Asp-Ser-Gly-Pro-Arg-Arg-Tyr-Thr-Ile-Ala-Ala-Leu-Leu-Ser-Pro-Tyr-Ser-Tyr-Ser-Thr-Thr-Ala-Val-Val-Thr-Asn-Pro-Lys-Glu-COOH.