Characterization of natural and artificial mutants of human intestinal lactase phlorizin hydrolase Lactase phlorizin hydrolase congenital lactase deficiency folding intramolecular organisation trafficking detergent resistant membranes. Laktase Phlorizin Hydrolase congenitale Laktase Defizienz Faltung intramolekulare Organisation Zielsteuerung Detergenz resistente Membranen