In addition to polymerase activity, this DNA polymerase exhibits 3'-5' exonuclease activity. a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) DNA polymerase is inhibited by replication protein A (RPA), while 3'-5' exonuclease activity is not. Polymerase inhibition can be overcome by replication factor C (RFC) and PCNA. Optimum temperature for DNA polymerase is 60 degrees Celsius, functional between 60 and 80 degrees Celsius. Exonuclease activity is higher at 70 than 50 degrees Celsius. Formed of a complex between PolB1 and PolB2; the exonuclease activity is associated with subunit 1. Probably binds replication protein A (RPA). In some Methanobacteriaceae the PolB protein is split over 2 genes. Belongs to the DNA polymerase type-B family.