The class B, type I scavenger receptor (Srb1 or Scarb1) is a cell surface HDL receptor. It plays a key role in determining the levels of plasma lipoprotein cholesterol (primarily HDL) and the accumulation of cholesterol stores in the adrenal gland. Homozygous females are infertile if the diet is not supplemented with probucol; homozygous males are fertile. A cross between heterozygotes will generate homozygous pups at a normal mendelian ratio if the breeding pair are fed with a probucol supplemented diet.