DNA polymerase beta is not essential for the formation of palindromic (P) region of T cell receptor gene

Formation of palindromic (P) region at the variable (V)-diversity (D)-joini ng (J) junction in DNA polymerase beta (pol-beta) deficient mice were inves tigated by sequencing of reverse transcriptase-polymerase chain reaction (R T-PCR) products of mRNAs encoding the beta chain of T cell receptor (TCR). Total 42 and 43 cDNA clones encoding V-beta8-D-beta-J(beta)-C-beta from E18 .5 embryonic thymocytes of pol-beta gene knocked-out and wild type control mouse, respectively, were sequenced. Among them five and six clones from po l-beta knocked-out and wild type, respectively, have P insertions of two nu cleotides. This result unequivocally indicates that pol-beta, which is one of the repair-type DNA polymerases most abundantly expressed in thymus and spleen, is not essential for the formation of P region. (C) 2001 Elsevier S cience B.V. All rights reserved.