THE SMALL SUBUNITS OF HUMAN AND MOUSE DNA-POLYMERASE-EPSILON ARE HOMOLOGOUS TO THE 2ND LARGEST SUBUNIT OF THE YEAST SACCHAROMYCES-CEREVISIAE DNA-POLYMERASE-EPSILON

Human DNA polymerase epsilon is composed of a 261 kDa catalytic polype ptide and a 55 kDa small subunit of unknown function. cDNAs encoding t he small subunit of human and mouse DNA polymerase epsilon were cloned . The predicted polypeptides have molecular masses of 59.469 and 59.31 9 kDa respectively and they are 90% identical. The human and mouse pol ypeptides show 22% identity with the 80 kDa subunit of the five subuni t DNA polymerase epsilon from the yeast Saccharomyces cerevisiae. The high degree of conservation suggests that the 55 kDa subunit shares an essential function with the yeast 80 kDa subunit, which was earlier s uggested to be involved in S phase cell cycle control in a pathway tha t is able to sense and signal incomplete replication. The small subuni ts of human and mouse DNA polymerase epsilon also show homology to the C-terminal domain of the second largest subunit of DNA polymerase alp ha. The gene for the small subunit of human DNA polymerase epsilon (PO LE2) was localized to chromosome 14q21-q22 by fluorescence in situ hyb ridization.