Molecular cloning of olfactomedin, an extracellular matrix protein specific to olfactory neuroepithelium.

The extracellular mucous matrix of olfactory neuroepithelium is a highly organized structure in intimate contact with chemosensory cilia that house the olfactory transduction machinery. Here we describe the molecular cloning and primary structure of olfactomedin, which is the major component of this extracellular matrix. Olfactomedin is expressed exclusively in olfactory neuroepithelium and its amino acid sequence shows no homologies to any known protein. This olfactory tissue-specific glycoprotein contains cysteines which form disulfide-linked polymers that constitute the primary architecture of the olfactory extracellular matrix. By analogy to other extracellular matrix proteins of the nervous system, olfactomedin may influence the maintenance, growth, or differentiation of chemosensory cilia on the apical dendrites of olfactory neurons.