Protein component of the very low density lipoprotein (VLDL) of egg-laying females. Potent lipoprotein lipase inhibitor, preventing the loss of triglycerides from VLDL on their way from the liver to the growing oocytes. Homodimer; disulfide-linked. Produced by the liver, secreted into the blood and then sequestred by receptor mediated endocytosis into growing oocytes. ApoII mRNA induction by estrogen in kidney at day 11 is at 10% of the level in the liver but estrogen-responsiveness decreases later in development and is low in the adult. By steroids (estrogen). Belongs to the apovitellenin family.