Sucrase-isomaltase: A unique model to study specific cell-biological processes

Abstract

Sucrase-isomaltase is a type II transmembrane glycoprotein that is expressed at the brush-border of epithelial cells in the small intestine where it is important for the degradation of sucrose and some of the products of starch digestion. The unique expression pattern of SI together with its specific structural features makes the protein ideally suited as a model for several cell-biological processes. This will be illustrate in this review by the following topics: i) the special structural features of SI ii) the specific expression pattern of this protein and its regulation iii) the role of apical transport mechanisms in the transport of SI to the apical membrane iv) the mechanisms responsible for the transport failures that cause congenital SI deficiencies v) the role of SI in the signal transduction cascade that takes place upon binding of a bacterial toxin to SI.