The  active form of
   DNA  polymerase  III is called a holoenzyme, a dimer with 10 different
   polypeptide subunits.

   The  a  (alpha),  e (epsilon) and th (theta) subunits make up the core
   enzyme to perform polymerization and proofreading.

   The  g  (gamma)  complex  is involved in "loading" the enzyme onto the
   template at the replication fork.

   The  b (beta) subunit serves as a "clamp" and prevents the core enzyme
   from falling off the template during polymerization.

   The  t  (tau)  subunit  functions  to  dimerize  two  core polymerases
   allowing simultaneous synthesis of both strands of the helix.

   The  holoenzyme  and  several  other  proteins at the replication fork
   together form a huge complex called the replisome.