SI
Function
Plays an important role in the final stage of carbohydrate digestion. Isomaltase activity is specific for both alpha-1,4- and alpha-1,6-oligosaccharides.
Involvement in disease
Congenital sucrase-isomaltase deficiency
CSID
Autosomal recessive intestinal disorder that is clinically characterized by fermentative diarrhea, abdominal pain, and cramps upon ingestion of sugar. The symptoms are the consequence of absent or drastically reduced enzymatic activities of sucrase and isomaltase. The prevalence of CSID is 0.02 % in individuals of European descent and appears to be much higher in Greenland, Alaskan, and Canadian native people. CSID arises due to post-translational perturbations in the intracellular transport, polarized sorting, aberrant processing, and defective function of SI.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
The precursor is proteolytically cleaved when exposed to pancreatic proteases in the intestinal lumen.
Sulfated.
Sequence Similarities
Belongs to the glycosyl hydrolase 31 family.
Tissue Specificity
Expressed in the poorly differentiated crypt cells of the small intestine as well as in the mature villous cells. Expressed at very low levels in the colon.
Cellular localization
- Apical cell membrane
- Single-pass type II membrane protein
- Brush border.
Alternative names
SI