Methods for identifying and isolating tissue-specific lumen-exposed molecules

This invention provides novel methods of and kits for labeling and isolating lumen-exposed molecules, particularly polypeptides which are expressed in a tissue-specific or organ-specific manner. The methods and kits can be used to isolate molecules exposed on the luminal side of cells lining vascular, ductal, sinus, respiratory, fascial, and other perfusible tissue spaces.