The mammalian acetylcholinesterase (ACHE) locus was investigated using computational predictive methods and experiments of reverse transcription polymerase chain reaction (RT-PCR). Computational analysis identified two genes downstream to ACHE, an inversely oriented arsenite resistance gene homologue (ARS), and a novel previously unidentified gene (PIX), co-oriented with ACHE. Experimental evidence shows coregulation of murine ACHE and ARS following confined swim, indicating coordinated locus response to stress, that is possibly mediated by altered cholinergic neurotransmission.