The sucrase-isomaltase complex: Primary structure, membrane-orientation, and evolution of a stalked, intrinsic brush border protein

  title={The sucrase-isomaltase complex: Primary structure, membrane-orientation, and evolution of a stalked, intrinsic brush border protein},
  author={Walter Hunziker and Martin Spiess and Giorgio Semenza and Harvey F. Lodish},
Sucrase Is an Intramolecular Chaperone Located at the C-terminal End of the Sucrase-Isomaltase Enzyme Complex*
The interaction between SUC and the membrane-anchored IM leads to maturation of IM and blocks the secretion of SUC into the external milieu, concluding that SUC plays a role as an intramolecular chaperone in the context of the pro-SI protein.
Structure-function analysis of human sucrase-isomaltase identifies key residues required for catalytic activity
This approach provides a model for functional analysis of the single subunits within a multidomain protein, achieved without the necessity to express the individual subunits separately, and demonstrates that glucose product inhibition regulates the activities of both SI subunits.
Molecular dissection of the NH2-terminal signal/anchor sequence of rat dipeptidyl peptidase IV
Structural features of the DPPIV amino-terminal signal-anchor sequences are discussed along with other types of sequences for their role in targeting nascent polypeptides to the RER.
Molecular Dissection of the NH 2-Terminal Signal / Anchor Sequence of Rat Dipeptidyl Peptidase IV
  • Biology, Chemistry
  • 2002
Site-directed mutagenesis studies show that deletion of this cytoplasmic domain does not affect translocation of nascent DPPIV polypeptide, but does affect significantly anchoring of the translocated polyPEptide in the microsomal membrane.
Congenital sucrase-isomaltase deficiency. Identification of a glutamine to proline substitution that leads to a transport block of sucrase-isomaltase in a pre-Golgi compartment.
This is the first report that characterizes a point mutation in the SI gene that is responsible for the transport incompetence of SI and for its retention between the ER and the Golgi.
Primary structure and processing of the Candida tsukubaensisα‐glucosidase
N-Terminal amino acid sequence analysis of the individual subunits of the purified enzyme, expressed in the recombinant host Saccharomyces cerevisiae, confirmed that the α-glucosidase precursor is proteolytically processed by removal of an N-terminal signal peptide to yield the two peptide subunits 1 and 2.
Additional N-Glycosylation and Its Impact on the Folding of Intestinal Lactase-phlorizin Hydrolase*
The data strongly suggest that the LAC236 is implicated in the dimerization process of pro-LPH, most likely by nucleating the association of the ectodomains of the enzyme.
Characteristics and Structural Requirements of Apical Sorting of the Rat Growth Hormone through the O-Glycosylated Stalk Region of Intestinal Sucrase-isomaltase*
The O-glycans in the stalk region of SI act as an apical sorting signal within a sorting machinery that comprises at least a carbohydrate-binding protein and fulfills specific spatial requirements provided, for example by a polyglycine spacer in the context of rGH or the P-domain within the SI enzyme complex.
A study of the molecular pathology of sucrase-isomaltase deficiency. A defect in the intracellular processing of the enzyme.
Studies in a patient with primary sucrase-isomaltase deficiency demonstrated normal translation and high-mannose glycosylation of the precursor but a failure in further processing of the oligosaccharides, with subsequent intracellular degradation of the glycoprotein and undetectable enzymatic activity of intestinal sucrases.


Topology and quaternary structure of pro-sucrase/isomaltase and final-form sucrase/isomaltase.
Pig sucrase/isomaltase was purified from intestinal microvillar vesicles prepared from animals with and without pancreatic-duct ligation to obtain the single-chain pro form and the proteolytically cleaved final form respectively, and shows a homodimeric functional organization similar to that of other microVillar hydrolases.
Biogenesis of intestinal plasma membrane: posttranslational route and cleavage of sucrase-isomaltase.
Data suggest that pancreatic proteases may play an important role in the late posttranslational processing of sucrase-isomaltase in vivo, and is synthesized as a one-chain polypeptide precursor that is split into the subunits after its transfer to the microvillus membrane.
Partial amino acid sequences around the essential carboxylate in the active sites of the intestinal sucrase-isomaltase complex.
After peptic digestion of the labeled, denatured, reduced, and cyanoethylated enzyme three radioactive peptides were isolated and the radioactive label was in each case bound to the beta carboxyl group of an aspartic acid residue.
A simplified procedure for the isolation of the sucrase-isomaltase complex from rabbit intestine. Its amino-acid and sugar composition.
A simplified procedure for the isolation of the sucrase · isomaltase complex from rabbit small intestine was worked out, which allows the preparation of this protein in a homogeneous form in good