9316981 Aguilera The goal of this research is to further characterize the molecular and biochemical mechanisms involved in lymphocyte- specific DNA recombination. We have isolated and partially characterized a nuclease activity, Endo-S, which we believe is intimately involved in the isotype switch recombination process. We will continue to biochemically characterize Endo-S, sequence the native protein derived from it and generate a specific antisera to it. We will attempt to clone the gene encoding Endo-S and express it. We will also isolate and characterize any factors associated with it. %%% It is thought that this endonuclease, Endo-S, is involved in the DNA rearrangements which account for the large numbers of different antibodies which can be made by mammals. There is also suggestive evidence that it may also be involved in somatic DNA rearrangements which could have less desirable consequences, such as DNA translocations associated with oncogenes. A complete characterization of this protein could lead to a better understanding of its functional role in several different cellular processes. ***
