Generation of a rat bronchiolar epithelial cell cDNA library: isolation of a proline rich protein highly enriched in bronchiolar epithelial cells.

As a tool for the identification of novel gene products expressed in rat bronchiolar epithelial (BE) cells we generated a cDNA library prepared from BE cells, enriched to contain > 40% Clara cells. Using a simple differential screening strategy we isolated and partially characterized 47 clones, 29 of which corresponded to gene products known to be expressed within the bronchiolar epithelium. A further 15 clones contained sequences which were not present in the EMBL database and therefore represented potential novel BE cell enriched clones. One of these clones, CC-4, was characterized further and shown by northern blotting to be highly enriched in the BE cell population. The deduced protein product of CC-4 is a proline rich protein of 29.5 kd. These studies suggest that this cDNA library may be a useful tool for the identification of novel lung restricted gene products.