Vg2

Vg2, short for vitellogenin 2, is a member of the vitellogenin gene family that encodes a yolk protein precursor in many oviparous animals. In species with multiple vitellogenin genes, Vg2 is the second paralog, typically alongside Vg1. The gene products are large lipoglycoproteins that serve as nutrient-rich precursors stored in developing eggs.

During oogenesis, Vg2 is synthesized by tissues outside the ovary (commonly the liver in vertebrates and the fat body in insects) and released into the circulation. It is taken up by oocytes through receptor-mediated endocytosis and processed into yolk components such as lipovitellin and phosvitin, which nourish the embryo.

Expression of Vg2 is developmentally and tissue-specific and is often hormonally regulated. In vertebrates, hepatic Vg genes are typically estrogen-responsive and used as biomarkers for estrogenic exposure. In insects and other invertebrates, vitellogenin expression is governed by lineage-specific hormonal cues, and Vg2 contributes to yolk provisioning in eggs.

Vg2 genes vary across taxa in copy number and arrangement, commonly found in tandem with Vg1 in species with expanded vitellogenin repertoires. They are widely used in reproductive biology and environmental toxicology research to study yolk protein formation and endocrine disruption. See also vitellogenin and Vg1.