GENES ENCODING COMPONENTS OF THE OLFACTORY SIGNAL-TRANSDUCTION CASCADE CONTAIN A DNA-BINDING SITE THAT MAY DIRECT NEURONAL EXPRESSION

Genes which mediate odorant signal transduction are expressed at high levels in neurons of the olfactory epithelium. The molecular mechanism governing the restricted expression of these genes likely involves ti ssue-specific DNA binding proteins which coordinately activate transcr iption through sequence-specific interactions with olfactory promoter regions. We have identified binding sites for the olfactory neuron-spe cific transcription factor, Olf-1, in the sequences surrounding the tr anscriptional initiation site of five olfactory neuron-specific genes. The Olf-1 binding sites described define the consensus sequence YTCCC YRGGGAR. In addition, we have identified a second binding site, the U site, in the olfactory cyclic nucleotide gated channel and type III cy clase promoters, which binds factors present in all tissues examined. These experiments support a model in which expression of Olf-I in the sensory neurons coordinately activates a set of olfactory neuron-speci fic genes. Furthermore, expression of a subset of these genes may be m odulated by additional binding factors.