To assess the impact of various heavy and light chain mutations on p-azophenylarsonate binding, murine antibodies have been produced in insect cells (SF9) utilizing a baculovirus expression system. When expressed in this system, an antibody composed of a canonical CRIA+ heavy and light chain can bind antigen and express idiotype indistinguishably from analogous hybridoma-derived antibodies. Antibodies comprised of either light chains mutant at the V-J junction or heavy chains mutant at the V-D junction were found to be incapable of binding arsonate. In addition, substitutions in the first and second complementarity determining regions of the heavy chain were shown to play a role in arsonate binding, most likely related to affinity maturation targeted at the carrier protein. These results confirm the obligatory role that junctional diversity plays in the generation of arsonate-specific antibodies, as well as extend our understanding of the role of other variable region amino acids in arsonate binding.