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Aliases for SI Gene

Aliases for SI Gene

  • Sucrase-Isomaltase (Alpha-Glucosidase) 2 3
  • Oligosaccharide Alpha-1,6-Glucosidase 2
  • Sucrase-Isomaltase 2
  • 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 (Alpha-Glucosidase)) 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 Metabolism and Metabolism. GO annotations related to this gene include carbohydrate binding and oligo-1,6-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

164,978,898 bp from pter
165,078,495 bp from pter
99,598 bases
Minus strand

Genomic View for SI Gene

UCSC Golden Path with GeneCards custom track
Cytogenetic band:
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 Asn99, Asn437, Asn455, Asn823, Asn855, Asn904, Asn926, Asn1235, Asn1303, Asn1340, Asn1354, Asn1403, Asn1535, Asn1572, Asn1675, Asn1748, Asn1763, and Asn1815
  • Modification sites at PhosphoSitePlus

Other Protein References for SI Gene

ENSEMBL proteins:
Reactome Protein details:
REFSEQ proteins:

Domains 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:0003824 catalytic activity --
GO:0004553 hydrolase activity, hydrolyzing O-glycosyl compounds --
GO:0004558 alpha-1,4-glucosidase activity EXP --
GO:0004574 oligo-1,6-glucosidase activity IEA --
GO:0004575 sucrose alpha-glucosidase activity TAS --
genes like me logo Genes that share ontologies with SI: view

miRNA for SI Gene

miRTarBase miRNAs that target SI

No data available for Phenotypes , 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
plasma membrane 5
golgi apparatus 4
endoplasmic reticulum 2
extracellular 2
cytoskeleton 1
endosome 1
nucleus 1

Gene Ontology (GO) - Cellular Components for SI Gene

GO ID Qualified GO term Evidence PubMed IDs
GO:0005794 Golgi apparatus TAS 1717481
GO:0005886 plasma membrane TAS --
GO:0005903 brush border TAS 1717481
GO:0016020 membrane --
GO:0016021 integral component of membrane IEA --
genes like me logo Genes that share ontologies with SI: view

Pathways for SI Gene

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

Gene Ontology (GO) - Biological Process for SI Gene

GO ID Qualified GO term Evidence PubMed IDs
GO:0005975 carbohydrate metabolic process TAS --
GO:0044245 polysaccharide digestion TAS --
GO:0044281 small molecule metabolic process TAS --
genes like me logo Genes that share ontologies with SI: view

Drugs for SI Gene

(2) Drugbank Compounds for SI Gene

Compound Status Synonyms Cas Number PubChem ID Type Actions PubMed IDs
  • Acarbosa
56180-94-0 441184 Target inhibitor approved, investigational
  • (-)-hyoscine
51-34-3 Target inhibitor approved

(9) HMDB Compounds for SI Gene

Compound Synonyms Cas Number PubMed IDs
  • a-D-Glucopyranose
  • British gum
  • beta-D-Arabino-hexulose
  • Roferose ST

(62) Novoseek inferred chemical compound relationships for SI Gene

Compound -log(P) Hits PubMed IDs
kotalanol 85 3
salacinol 79 5
palatinose 65.5 3
sucrose 59.4 21
lactose 56.4 4
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 differential expression in normal tissues according to GTEx for SI Gene

This gene is overexpressed in Small Intestine - Terminal Ileum (46.9) and Colon - Transverse (4.6).

Protein differential expression in normal tissues for SI Gene

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

Integrated Proteomics: protein expression 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 expressions with SI: view

Expression partners for SI Gene

* - Elite partner

Primer Products

In Situ Assay Products

No data available for mRNA expression in embryonic tissues and stem cells from LifeMap Discovery for SI Gene

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 MAF
rs1079879 -- 164,992,252(-) AATGG(C/G/T)TATTT intron-variant
rs1457797 -- 164,999,975(+) ATTTA(A/G)Gaata intron-variant
rs1457801 -- 164,986,682(-) GCACA(A/C)GTTAA intron-variant
rs1457802 -- 165,005,663(-) actca(A/G)gaatg intron-variant
rs1817263 -- 165,026,204(+) acaaa(C/T)tttaa intron-variant

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

Relevant External Links for SI Gene

HapMap Linkage Disequilibrium report
Human Gene Mutation Database (HGMD)

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

Disorders for SI Gene

(1) OMIM Diseases for SI Gene (609845)


  • 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.

(2) University of Copenhagen DISEASES for SI Gene

(40) Novoseek inferred disease relationships for SI Gene

Disease -log(P) Hits PubMed IDs
disaccharide intolerance 77.5 1
lactase deficiency 77.1 3
colon adenocarcinoma 65.3 9
viral leukemia 55.3 2
diarrhea chronic 53.2 2

Genatlas disease for SI Gene

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

No data available for External Links for SI Gene

Publications for SI Gene

  1. 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. (PMID: 8609217) Ouwendijk J. … Naim H.Y. (J. Clin. Invest. 1996) 3 4 23
  2. Congenital sucrase-isomaltase deficiency arising from cleavage and secretion of a mutant form of the enzyme. (PMID: 10903344) Jacob R. … Naim H.Y. (J. Clin. Invest. 2000) 3 4 23
  3. Congenital sucrase-isomaltase deficiency because of an accumulation of the mutant enzyme in the endoplasmic reticulum. (PMID: 14724820) Ritz V. … Naim H.Y. (Gastroenterology 2003) 3 4 23
  4. 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 4 23
  5. Isolation of a cDNA probe for a human jejunal brush-border hydrolase, sucrase-isomaltase, and assignment of the gene locus to chromosome 3. (PMID: 2962903) Green F. … Swallow D. (Gene 1987) 2 3 4

Products for SI Gene

Sources for SI Gene

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