PROSITE documentation PDOC00186
Albumin domain signature and profile


The following serum transport proteins are known to be evolutionary related [1,2,3]:

  • Albumin (ALB), the main protein of plasma. It binds water, cations such as Ca++, Na+, K+, fatty acids, hormones, bilirubin and drugs. Its main function is the regulation of the colloidal osmotic pressure of blood.
  • α-fetoprotein (AFP) (α-fetoglobulin). AFP is a fetal plasma protein which also binds various cations, fatty acids and bilirubin.
  • Vitamin D-binding protein (VDB), also known as group-specific component or Gc-globulin. VDB binds to vitamin D and its metabolites as well as fatty acids.
  • Afamin (or α-albumin), a protein whose biochemical role is not yet characterized.

Structurally, these proteins consist of two to seven homologous domains of about 190 amino acids. Each domain, consisting of 10 α-helices, is formed by two smaller subdomains and contains five or six internal disulfide bonds as shown in the following schematic representation [4].

                    +---+          +----+                        +-----+
                    |   |          |    |                        |     |
   |                 |       |      |             |            ***|********
   +-----------------+       +------+             +---------------+
'C': conserved cysteine involved in a disulfide bond.
'*': position of the pattern.

The signature pattern we derived is based on three conserved cysteines at the end of the domain. We built it in such a way that it can detect all 3 repeats in albumin and human afamin, the first two in AFP and the first one in VDB and rat afamin. We also developed a profile, which covers the entire albumin domain.

Last update:

March 2009 / Text revised; profile added.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

ALBUMIN_2, PS51438; Albumin domain profile  (MATRIX)

ALBUMIN_1, PS00212; Albumin domain signature  (PATTERN)


1AuthorsHaefliger D.N. Moskaitis J.E. Schoenberg D.R. Wahli W.
TitleAmphibian albumins as members of the albumin, alpha-fetoprotein, vitamin D-binding protein multigene family.
SourceJ. Mol. Evol. 29:344-354(1989).
PubMed ID2481749

2AuthorsSchoentgen F. Metz-Boutigue M.-H. Jolles J. Constans J. Jolles P.
TitleComplete amino acid sequence of human vitamin D-binding protein (group-specific component): evidence of a three-fold internal homology as in serum albumin and alpha-fetoprotein.
SourceBiochim. Biophys. Acta 871:189-198(1986).
PubMed ID2423133

3AuthorsLichenstein H.S. Lyons D.E. Wurfel M.M. Johnson D.A. McGinley M.D. Leidli J.C. Trollinger D.B. Mayer J.P. Wright S.D. Zukowski M.M.
TitleAfamin is a new member of the albumin, alpha-fetoprotein, and vitamin D-binding protein gene family.
SourceJ. Biol. Chem. 269:18149-18154(1994).
PubMed ID7517938

4AuthorsHe X.M. Carter D.C.
TitleAtomic structure and chemistry of human serum albumin.
SourceNature 358:209-215(1992).
PubMed ID1630489

5AuthorsVerboven C. Rabijns A. De Maeyer M. Van Baelen H. Bouillon R. De Ranter C.
TitleA structural basis for the unique binding features of the human vitamin D-binding protein.
SourceNat. Struct. Biol. 9:131-136(2002).
PubMed ID11799400

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