Disaccharidase: localization in hamster intestine brush borders.

Electron microscopy of isolated brush borders from epithelial cells of hamster intestine demonstrates 60-angstrom knobs attached to the lumen surface of the plasma membrane. Digestion with activated papain removes these knobs. Separation and recovery of the knobs and the plasma membrane are possible. The activities of the disaccharidases invertase and maltase reside in the knobs and are not found with the plasma membrane.