Vitellogenin is an egg yolk precursor found in the females of nearly all oviparous species including fish, amphibians, reptiles, birds, most invertebrates, and monotremes.
In the presence of estrogenic endocrine disruptive chemicals (EDCs), male fish can express the gene in a dose dependent manner.
[3] Vitellogenin provides the major egg yolk protein that is a source of nutrients during early development of egg-laying (oviparous) vertebrates and invertebrates.
[10] APOB (see native LDL-ApoB structure at 37°C on YouTube);[11] MTTP; Honey bees deposit vitellogenin molecules in fat bodies in their abdomen and heads.
As expendable laborers, the foragers are fed just enough protein to keep them working their risky task of collecting nectar and pollen.
Vitellogenin levels are important during the nest stage and thus influence honey bee worker division of labor.
If young workers are short on food their first days of life, they tend to begin foraging early and preferentially for nectar.
If they are abundantly fed, immediately after emergence, their vitellogenin titer is high and they begin foraging later in life, preferentially collecting pollen.
With the exception of monotremes, mammals have all their vitellogenin genes turned into pseudogenes, although the region syntenic to bird VIT1-VIT2-VIT3 can still be found and aligned.