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Aliases for SI Gene

Aliases for SI Gene

  • Sucrase-Isomaltase 2 3
  • Sucrase-Isomaltase (Alpha-Glucosidase) 2 3 5
  • Oligosaccharide Alpha-1,6-Glucosidase 2 3
  • Alpha-Glucosidase 2 3
  • EC 63

External Ids for SI Gene

Previous GeneCards Identifiers for SI Gene

  • GC03M161906
  • GC03M165752
  • GC03M166071
  • GC03M166017
  • GC03M166179
  • GC03M164696
  • GC03M162066

Summaries for SI Gene

Entrez Gene Summary for SI Gene

  • This gene encodes a sucrase-isomaltase enzyme that is expressed in the intestinal brush border. The encoded protein is synthesized as a precursor protein that is cleaved by pancreatic proteases into two enzymatic subunits sucrase and isomaltase. These two subunits heterodimerize to form the sucrose-isomaltase complex. This complex is essential for the digestion of dietary carbohydrates including starch, sucrose and isomaltose. Mutations in this gene are the cause of congenital sucrase-isomaltase deficiency.[provided by RefSeq, Apr 2010]

GeneCards Summary for SI Gene

SI (Sucrase-Isomaltase) is a Protein Coding gene. Diseases associated with SI include Sucrase-Isomaltase Deficiency, Congenital and Congenital Sucrase-Isomaltase Deficiency With Starch Intolerance. Among its related pathways are Glycosaminoglycan metabolism and Galactose metabolism. GO annotations related to this gene include carbohydrate binding and alpha-1,4-glucosidase activity. An important paralog of this gene is MGAM.

UniProtKB/Swiss-Prot for SI Gene

  • 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.

No data available for Tocris Summary , Gene Wiki entry , PharmGKB "VIP" Summary , fRNAdb sequence ontologies and piRNA Summary for SI Gene

Genomics for SI Gene

Regulatory Elements for SI Gene

Genomic Location for SI Gene

164,978,893 bp from pter
165,078,495 bp from pter
99,603 bases
Minus strand

Genomic View for SI Gene

Genes around SI on UCSC Golden Path with GeneCards custom track

Cytogenetic band:
SI Gene in genomic location: bands according to Ensembl, locations according to GeneLoc (and/or Entrez Gene and/or Ensembl if different)
Genomic Location for SI Gene
GeneLoc Logo Genomic Neighborhood Exon StructureGene Density

RefSeq DNA sequence for SI Gene

Proteins for SI Gene

  • Protein details for SI Gene (UniProtKB/Swiss-Prot)

    Protein Symbol:
    Recommended name:
    Sucrase-isomaltase, intestinal
    Protein Accession:
    Secondary Accessions:
    • A2RUC3
    • Q1JQ80
    • Q1RMC2

    Protein attributes for SI Gene

    1827 amino acids
    Molecular mass:
    209453 Da
    Quaternary structure:
    • The resulting sucrase and isomaltase subunits stay associated with one another in a complex by non-covalent linkages.
    • There is a high degree of homology between the isomaltase and sucrase portions (41% of amino acid identity) indicating that this protein is evolved by partial gene duplication.

    Three dimensional structures from OCA and Proteopedia for SI Gene

neXtProt entry for SI Gene

Proteomics data for SI Gene at MOPED

Selected DME Specific Peptides for SI Gene

Post-translational modifications for SI Gene

  • Sulfated.
  • The precursor is proteolytically cleaved when exposed to pancreatic proteases in the intestinal lumen.
  • Glycosylation at Asn 99, Asn 437, Asn 455, Asn 823, Asn 855, Asn 904, Asn 926, Asn 1235, Asn 1303, Asn 1340, Asn 1354, Asn 1403, Asn 1535, Asn 1572, Asn 1675, Asn 1748, Asn 1763, and Asn 1815
  • Modification sites at PhosphoSitePlus

Other Protein References for SI Gene

ENSEMBL proteins:
REFSEQ proteins:

Domains & Families for SI Gene

Suggested Antigen Peptide Sequences for SI Gene

GenScript: Design optimal peptide antigens:

Graphical View of Domain Structure for InterPro Entry



  • Contains 2 P-type (trefoil) domains.
  • Belongs to the glycosyl hydrolase 31 family.
  • Contains 2 P-type (trefoil) domains.
  • Belongs to the glycosyl hydrolase 31 family.
genes like me logo Genes that share domains with SI: view

No data available for Gene Families for SI Gene

Function for SI Gene

Molecular function for SI Gene

GENATLAS Biochemistry:
sucrase-isomaltase,alpha D-glucosidase from intestinal mucosa that hydrolyzes sucrose and isomaltose,member of the glycosyl hydrolase family 3
UniProtKB/Swiss-Prot CatalyticActivity:
Hydrolysis of sucrose and maltose by an alpha-D-glucosidase-type action.
UniProtKB/Swiss-Prot CatalyticActivity:
Hydrolysis of (1->6)-alpha-D-glucosidic linkages in some oligosaccharides produced from starch and glycogen by alpha-amylase, and in isomaltose.
UniProtKB/Swiss-Prot 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.

Enzyme Numbers (IUBMB) for SI Gene

Gene Ontology (GO) - Molecular Function for SI Gene

GO ID Qualified GO term Evidence PubMed IDs
GO:0004574 oligo-1,6-glucosidase activity IEA --
genes like me logo Genes that share ontologies with SI: view
genes like me logo Genes that share phenotypes with SI: view

Human Phenotype Ontology for SI Gene

HPO Id HPO Name Alternative Ids Definition Synonyms

miRNA for SI Gene

miRTarBase miRNAs that target SI

No data available for Animal Models , Transcription Factor Targets and HOMER Transcription for SI Gene

Localization for SI Gene

Subcellular locations from UniProtKB/Swiss-Prot for SI Gene

Apical cell membrane; Single-pass type II membrane protein. Note=Brush border.

Subcellular locations from

Jensen Localization Image for SI Gene COMPARTMENTS Subcellular localization image for SI gene
Compartment Confidence
extracellular 5
golgi apparatus 5
plasma membrane 5
endoplasmic reticulum 3

Gene Ontology (GO) - Cellular Components for SI Gene

GO ID Qualified GO term Evidence PubMed IDs
GO:0005903 brush border TAS 1717481
GO:0016324 apical plasma membrane IEA --
genes like me logo Genes that share ontologies with SI: view

Pathways & Interactions for SI Gene

genes like me logo Genes that share pathways with SI: view

Gene Ontology (GO) - Biological Process for SI Gene


No data available for SIGNOR curated interactions for SI Gene

Drugs & Compounds for SI Gene

(35) Drugs for SI Gene - From: DrugBank, DGIdb, HMDB, and Novoseek

Name Status Disease Links Group Role Mechanism of Action Clinical Trials
Acarbose Approved, Investigational Pharma inhibitor, Target Alpha-glucosidase inhibitor, Glucosidase alpha inhibitor (intestinal) 81
Scopolamine Approved Pharma Antagonist, Target, inhibitor 0
Sucrose Experimental Pharma 0

(34) Additional Compounds for SI Gene - From: Novoseek and HMDB

Name Synonyms Role CAS Number PubChem IDs PubMed IDs
  • 6-O-a-D-Glucopyranosyl-D-glucose
  • 6-O-alpha-D-Glucopyranosyl-D-glucose
  • 6-O-alpha-delta-Glucopyranosyl-delta-glucose
  • Brachiose
  • a-D-Glucopyranose
  • a-D-Glucose
  • a-Dextrose
  • a-Glucose
  • alpha-D-Glucopyranose
  • British gum
  • Caloreen
  • Corn dextrin
  • Crystal gum
  • Dextrid
  • beta-D-Arabino-hexulose
  • beta-D-Fructofuranose
  • beta-D-Fructose
  • beta-delta-Arabino-hexulose
  • beta-delta-Fructofuranose
  • Roferose ST
  • (+)-Glucose
  • Anhydrous dextrose
  • Cerelose
  • Cerelose 2001
genes like me logo Genes that share compounds with SI: view

Transcripts for SI Gene

mRNA/cDNA for SI Gene

Unigene Clusters for SI Gene

Sucrase-isomaltase (alpha-glucosidase):
Representative Sequences:

Alternative Splicing Database (ASD) splice patterns (SP) for SI Gene

ExUns: 1 ^ 2 ^ 3a · 3b · 3c ^ 4 ^ 5 ^ 6 ^ 7 ^ 8 ^ 9 ^ 10 ^ 11 ^ 12 ^ 13 ^ 14 ^ 15 ^ 16 ^ 17 ^ 18 ^ 19 ^ 20 ^ 21a · 21b ^ 22a · 22b ^
SP1: - -
SP2: -
SP7: -

ExUns: 23 ^ 24 ^ 25 ^ 26 ^ 27 ^ 28 ^ 29 ^ 30 ^ 31 ^ 32 ^ 33

Relevant External Links for SI Gene

GeneLoc Exon Structure for
ECgene alternative splicing isoforms for

Expression for SI Gene

mRNA expression in normal human tissues for SI Gene

mRNA expression in embryonic tissues and stem cells from LifeMap Discovery

mRNA differential expression in normal tissues according to GTEx for SI Gene

This gene is overexpressed in Small Intestine - Terminal Ileum (x46.9) and Colon - Transverse (x4.6).

Protein differential expression in normal tissues from HIPED for SI Gene

This gene is overexpressed in Pancreatic juice (58.8) and Fetal gut (10.1).

Integrated Proteomics: protein expression in normal tissues and cell lines from ProteomicsDB, PaxDb, MOPED, and MaxQB for SI Gene

SOURCE GeneReport for Unigene cluster for SI Gene Hs.429596

mRNA Expression by UniProt/SwissProt for SI Gene

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.
genes like me logo Genes that share expression patterns with SI: view

Protein tissue co-expression partners for SI Gene

- Elite partner

Primer Products

Orthologs for SI Gene

This gene was present in the common ancestor of animals.

Orthologs for SI Gene

Organism Taxonomy Gene Similarity Type Details
(Bos Taurus)
Mammalia SI 35
  • 86.41 (n)
  • 82.73 (a)
SI 36
  • 83 (a)
(Canis familiaris)
Mammalia SI 35
  • 87.53 (n)
  • 84.44 (a)
SI 36
  • 84 (a)
(Mus musculus)
Mammalia Sis 35
  • 79.88 (n)
  • 78.21 (a)
Sis 16
Sis 36
  • 78 (a)
(Pan troglodytes)
Mammalia SI 35
  • 99.4 (n)
  • 99.45 (a)
SI 36
  • 99 (a)
(Rattus norvegicus)
Mammalia Si 35
  • 77.38 (n)
  • 75.16 (a)
(Monodelphis domestica)
Mammalia SI 36
  • 73 (a)
(Ornithorhynchus anatinus)
Mammalia SI 36
  • 68 (a)
(Gallus gallus)
Aves -- 36
  • 48 (a)
-- 36
  • 39 (a)
(Anolis carolinensis)
Reptilia -- 36
  • 44 (a)
-- 36
  • 50 (a)
-- 36
  • 42 (a)
(Danio rerio)
Actinopterygii wufd44a09 35
CU914772.1 36
  • 37 (a)
(Caenorhabditis elegans)
Secernentea D2096.3 37
  • 38 (a)
F53F4.8 37
  • 35 (a)
R05F9.12 37
  • 36 (a)
aagr-1 36
  • 34 (a)
aagr-2 36
  • 33 (a)
sea squirt
(Ciona savignyi)
Ascidiacea -- 36
  • 44 (a)
-- 36
  • 40 (a)
Species with no ortholog for SI:
  • A. gosspyii yeast (Ashbya gossypii)
  • Actinobacteria (Mycobacterium tuberculosis)
  • African clawed frog (Xenopus laevis)
  • African malaria mosquito (Anopheles gambiae)
  • Alicante grape (Vitis vinifera)
  • alpha proteobacteria (Wolbachia pipientis)
  • amoeba (Dictyostelium discoideum)
  • Archea (Pyrococcus horikoshii)
  • baker's yeast (Saccharomyces cerevisiae)
  • barley (Hordeum vulgare)
  • beta proteobacteria (Neisseria meningitidis)
  • bread mold (Neurospora crassa)
  • Chromalveolata (Phytophthora infestans)
  • common water flea (Daphnia pulex)
  • corn (Zea mays)
  • E. coli (Escherichia coli)
  • filamentous fungi (Aspergillus nidulans)
  • Firmicute bacteria (Streptococcus pneumoniae)
  • fission yeast (Schizosaccharomyces pombe)
  • fruit fly (Drosophila melanogaster)
  • green algae (Chlamydomonas reinhardtii)
  • honey bee (Apis mellifera)
  • K. lactis yeast (Kluyveromyces lactis)
  • loblloly pine (Pinus taeda)
  • malaria parasite (Plasmodium falciparum)
  • medicago trunc (Medicago Truncatula)
  • moss (Physcomitrella patens)
  • orangutan (Pongo pygmaeus)
  • pig (Sus scrofa)
  • rainbow trout (Oncorhynchus mykiss)
  • rice (Oryza sativa)
  • rice blast fungus (Magnaporthe grisea)
  • schistosome parasite (Schistosoma mansoni)
  • sea anemone (Nematostella vectensis)
  • sea urchin (Strongylocentrotus purpuratus)
  • sorghum (Sorghum bicolor)
  • soybean (Glycine max)
  • stem rust fungus (Puccinia graminis)
  • sugarcane (Saccharum officinarum)
  • thale cress (Arabidopsis thaliana)
  • tomato (Lycopersicon esculentum)
  • toxoplasmosis (Toxoplasma gondii)
  • Trichoplax (Trichoplax adhaerens)
  • tropical clawed frog (Silurana tropicalis)
  • wheat (Triticum aestivum)

Evolution for SI Gene

Gene Tree for SI (if available)
Gene Tree for SI (if available)

Paralogs for SI Gene

Paralogs for SI Gene

(2) SIMAP similar genes for SI Gene using alignment to 2 proteins: Pseudogenes for SI Gene

genes like me logo Genes that share paralogs with SI: view

Variants for SI Gene

Sequence variations from dbSNP and Humsavar for SI Gene

SNP ID Clin Chr 03 pos Sequence Context AA Info Type
VAR_007854 Congenital sucrase-isomaltase deficiency (CSID)
VAR_025367 -
VAR_025368 Congenital sucrase-isomaltase deficiency (CSID)
rs9283633 - 165,065,377(+) ACGGG(C/T)TGAGA reference, missense
VAR_025370 Congenital sucrase-isomaltase deficiency (CSID)

Structural Variations from Database of Genomic Variants (DGV) for SI Gene

Variant ID Type Subtype PubMed ID
nsv428426 CNV Loss 18775914
dgv5331n71 CNV Loss 21882294
nsv829785 CNV Loss 17160897
dgv5332n71 CNV Loss 21882294
nsv518452 CNV Loss 19592680
esv2577226 CNV Deletion 19546169

Variation tolerance for SI Gene

Residual Variation Intolerance Score: 2% of all genes are more intolerant (likely to be disease-causing)
Gene Damage Index Score: 9.89; 89.75% of all genes are more intolerant (likely to be disease-causing)

Relevant External Links for SI Gene

Human Gene Mutation Database (HGMD)

No data available for Polymorphic Variants from UniProtKB/Swiss-Prot for SI Gene

Disorders for SI Gene

MalaCards: The human disease database

(8) MalaCards diseases for SI Gene - From: OMIM, ClinVar, GeneTests, Orphanet, Swiss-Prot, DISEASES, Novoseek, and GeneCards

- elite association - COSMIC cancer census association via MalaCards
Search SI in MalaCards View complete list of genes associated with diseases


  • Congenital sucrase-isomaltase deficiency (CSID) [MIM:222900]: 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. {ECO:0000269 PubMed:10903344, ECO:0000269 PubMed:11340066, ECO:0000269 PubMed:14724820, ECO:0000269 PubMed:16329100, ECO:0000269 PubMed:8609217}. Note=The disease is caused by mutations affecting the gene represented in this entry.

Genatlas disease for SI Gene

disaccharide intolerance

Relevant External Links for SI

Atlas of Genetics and Cytogenetics in Oncology and Haematology:
genes like me logo Genes that share disorders with SI: view

Publications for SI Gene

  1. Sequence of the complete cDNA and the 5' structure of the human sucrase-isomaltase gene. Possible homology with a yeast glucoamylase. (PMID: 1353958) Chantret I. … Rousset M. (Biochem. J. 1992) 2 3 4 67
  2. Structural basis for substrate selectivity in human maltase- glucoamylase and sucrase-isomaltase N-terminal domains. (PMID: 20356844) Sim L. … Rose D.R. (J. Biol. Chem. 2010) 3 23
  3. Compound heterozygous mutations affect protein folding and function in patients with congenital sucrase-isomaltase deficiency. (PMID: 19121318) Alfalah M. … Naim H.Y. (Gastroenterology 2009) 3 23
  4. HNF-1alpha participates in glucose regulation of sucrase-isomaltase gene expression in epithelial intestinal cells. (PMID: 17194452) Gu N. … Tsuda K. (Biochem. Biophys. Res. Commun. 2007) 3 23
  5. Novel mutations in the human sucrase-isomaltase gene (SI) that cause congenital carbohydrate malabsorption. (PMID: 16329100) Sander P. … Naim H.Y. (Hum. Mutat. 2006) 3 23

Products for SI Gene

Sources for SI Gene