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Protein

Sucrase-isomaltase, intestinal

Gene

SI

Organism
Sus scrofa (Pig)
Status
Reviewed-Annotation score: Annotation score: 4 out of 5-Experimental evidence at protein leveli

Functioni

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 (By similarity).By similarity

Catalytic activityi

Hydrolysis of sucrose and maltose by an alpha-D-glucosidase-type action.
Hydrolysis of (1->6)-alpha-D-glucosidic linkages in some oligosaccharides produced from starch and glycogen by alpha-amylase, and in isomaltose.

GO - Molecular functioni

  1. oligo-1,6-glucosidase activity Source: UniProtKB-EC
  2. sucrose alpha-glucosidase activity Source: UniProtKB-EC
Complete GO annotation...

Keywords - Molecular functioni

Glycosidase, Hydrolase

Names & Taxonomyi

Protein namesi
Recommended name:
Sucrase-isomaltase, intestinal
Cleaved into the following 2 chains:
Gene namesi
Name:SI
OrganismiSus scrofa (Pig)
Taxonomic identifieri9823 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaLaurasiatheriaCetartiodactylaSuinaSuidaeSus
ProteomesiUP000008227 Componenti: Unplaced

Subcellular locationi

  1. Apical cell membrane By similarity; Single-pass type II membrane protein By similarity

  2. Note: Brush border.By similarity

Topology

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Topological domaini2 – 1211CytoplasmicSequence AnalysisAdd
BLAST
Transmembranei13 – 3220Helical; Signal-anchor for type II membrane proteinSequence AnalysisAdd
BLAST
Topological domaini33 – ›38›6LumenalSequence Analysis

GO - Cellular componenti

  1. apical plasma membrane Source: UniProtKB-SubCell
  2. integral component of membrane Source: UniProtKB-KW
Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Membrane

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Initiator methioninei1 – 11Removed1 Publication
Chaini2 – ›38›37IsomaltasePRO_0000018554Add
BLAST
Chaini39 – ›62›24SucrasePRO_0000018555Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei7 – 71Phosphoserine; by PKABy similarity
Modified residuei59 – 591SulfotyrosineSequence Analysis

Post-translational modificationi

The precursor is proteolytically cleaved when exposed to pancreatic proteases in the intestinal lumen.
Sulfated.1 Publication

Keywords - PTMi

Phosphoprotein, Sulfation

Interactioni

Subunit structurei

The resulting sucrase and isomaltase subunits stay associated with one another in a complex by non-covalent linkages.

Family & Domainsi

Sequence similaritiesi

Belongs to the glycosyl hydrolase 31 family.Curated

Keywords - Domaini

Repeat, Signal-anchor, Transmembrane, Transmembrane helix

Sequencei

Sequence statusi: Fragments.

Sequence processingi: The displayed sequence is further processed into a mature form.

P56729-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MARKKFSGLE IXLIVLFAIV LSIAIALVVV XASKXPAVIK LPSDPIPTLR
60
MEMTYHTDYM LE
Length:62
Mass (Da):6,893
Last modified:January 23, 2007 - v2
Checksum:i7D4E3C6AFC5AFB8B
GO

Experimental Info

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Sequence uncertaintyi33 – 331
Sequence uncertaintyi34 – 341
Non-adjacent residuesi38 – 392Curated
Sequence uncertaintyi51 – 511M or V
Sequence uncertaintyi53 – 531M or V
Sequence uncertaintyi54 – 541T or K
Sequence uncertaintyi57 – 571T or K
Sequence uncertaintyi60 – 601M or V
Non-terminal residuei62 – 621

Sequence databases

PIRiA25987.

Cross-referencesi

Sequence databases

PIRiA25987.

3D structure databases

ModBaseiSearch...
MobiDBiSearch...

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Family and domain databases

ProtoNetiSearch...

Publicationsi

  1. "N-terminal sequences of pig intestinal sucrase-isomaltase and pro-sucrase-isomaltase. Implications for the biosynthesis and membrane insertion of pro-sucrase-isomaltase."
    Sjoestroem H., Noren O., Christiansen L.A., Wacker H., Spiess M., Bigler-Meier B., Rickli E.E., Semenza G.
    FEBS Lett. 148:321-325(1982) [PubMed] [Europe PMC] [Abstract]
    Cited for: PROTEIN SEQUENCE OF 2-62.
  2. "Tyrosine sulfation, a post-translational modification of microvillar enzymes in the small intestinal enterocyte."
    Danielsen E.M.
    EMBO J. 6:2891-2896(1987) [PubMed] [Europe PMC] [Abstract]
    Cited for: SULFATION.

Entry informationi

Entry nameiSUIS_PIG
AccessioniPrimary (citable) accession number: P56729
Entry historyi
Integrated into UniProtKB/Swiss-Prot: May 30, 2000
Last sequence update: January 23, 2007
Last modified: January 7, 2015
This is version 64 of the entry and version 2 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

Complete proteome, Direct protein sequencing, Multifunctional enzyme, Reference proteome

Documents

  1. Glycosyl hydrolases
    Classification of glycosyl hydrolase families and list of entries
  2. SIMILARITY comments
    Index of protein domains and families

External Data

Dasty 3

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into Uniref entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.