Precursor of the major egg-yolk proteins that are sources of nutrients during early development of oviparous organisms. Produced by the liver, secreted into the blood and then sequestered by receptor mediated endocytosis into growing oocytes, where it is generally cleaved, giving rise to the respective yolk components composed of complex suite of small cleavage products. Phosvitin, an egg yolk storage protein, is one of the most highly phosphorylated (10%) proteins in nature. The N-terminal of the blood vitellogenin is blocked.