Vitellogenin

High molecular weight yolk precursor protein (from lat. vitellum = yolk), which is formed in the animal kingdom by animals with yolk rich eggs (yolk) under the influence of oestrogen in the liver. Vitellogenin is a building block for lipoproteins and phosphoproteins, which the later embryo metabolises. In egg-laying invertebrates and wibrous animals, vitellogenesis involves the introduction of vitellogenin into the individual cell and its cleavage by the enzyme cathepsin.

Homologues of vitellogenin are used in animals and humans as transport proteins for triglycerides in the blood. The human apolipoprotein B-100 is homologous to vitellogenin. It is the only ligand of the LDL receptor. > 80 mutations in the coding APOB gene have been described so far. They cause familial hypobetalipoproteinemia (FHBL) with disorders of cllesterol metabolism and a slightly to moderately increased risk of CHD.

1. Tian X et al (2010) What makes an egg unique? Clues from evolutionary scenarios of egg-specific genes. Biol Reprod 83:893-900.
2. Westley B (1979) The relationship of the estrogen receptor to the induction of vitellogenin in chicken and Xenopus liver. Differentiation 15: 67-72.