The  gene  for  a  human  cholesterol  receptor contains 18 exons that
   encode 5 domains in the protein.

   Exons 2-6 comprise the domain for the binding site for cholesterol.

   The  next  8  exons  comprise a domain homologous to the mouse hormone
   epidermal  growth factor (EGF). A similar domain is also found in many
   other polypeptides, including 3 blood-clotting proteins.

   Other exons specify 3 domains that perform specific functions.