P56729 (SUIS_PIG) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Sucrase-isomaltase, intestinal

Cleaved into the following 2 chains:

1. Sucrase
   EC=3.2.1.48
2. Isomaltase
   EC=3.2.1.10

Gene names

Name:

SI

Organism

Sus scrofa (Pig) [Reference proteome]

Taxonomic identifier

9823 [NCBI]

Taxonomic lineage

cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Deuterostomia › Chordata › Craniata › Vertebrata › Gnathostomata › Teleostomi › Euteleostomi › Sarcopterygii › Tetrapoda › Amniota › Mammalia › Theria › Eutheria › Laurasiatheria › Cetartiodactyla › Suina › Suidae › Sus

Protein attributes

Sequence length	62 AA.
Sequence status	Fragments.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level

General annotation (Comments)

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 By similarity.
Catalytic activity	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.
Subunit structure	The resulting sucrase and isomaltase subunits stay associated with one another in a complex by non-covalent linkages.
Subcellular location	Apical cell membrane; Single-pass type II membrane protein By similarity. Note: Brush border By similarity.
Post-translational modification	The precursor is proteolytically cleaved when exposed to pancreatic proteases in the intestinal lumen. Sulfated.
Sequence similarities	Belongs to the glycosyl hydrolase 31 family.

Ontologies

Keywords
Cellular component	Cell membrane Membrane
Domain	Repeat Signal-anchor Transmembrane Transmembrane helix
Molecular function	Glycosidase Hydrolase
PTM	Phosphoprotein Sulfation
Technical term	Complete proteome Direct protein sequencing Multifunctional enzyme Reference proteome
Gene Ontology (GO)
Biological_process	carbohydrate metabolic process Inferred from electronic annotation. Source: InterPro
Cellular_component	apical plasma membrane Inferred from electronic annotation. Source: UniProtKB-SubCell integral to membrane Inferred from electronic annotation. Source: UniProtKB-KW
Molecular_function	oligo-1,6-glucosidase activity Inferred from electronic annotation. Source: EC sucrose alpha-glucosidase activity Inferred from electronic annotation. Source: EC
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Initiator methionine	1	1	Removed Ref.1
	Chain	2 – ›38	›37	Isomaltase		PRO_0000018554
	Chain	39 – ›62	›24	Sucrase		PRO_0000018555
Regions
	Topological domain	2 – 12	11	Cytoplasmic Potential
	Transmembrane	13 – 32	20	Helical; Signal-anchor for type II membrane protein; Potential
	Topological domain	33 – ›38	›6	Lumenal Potential
Amino acid modifications
	Modified residue	7	1	Phosphoserine; by PKA By similarity
	Modified residue	59	1	Sulfotyrosine Potential
Experimental info
	Sequence uncertainty	33	1
	Sequence uncertainty	34	1
	Sequence uncertainty	51	1	M or V
	Sequence uncertainty	53	1	M or V
	Sequence uncertainty	54	1	T or K
	Sequence uncertainty	57	1	T or K
	Sequence uncertainty	60	1	M or V
	Non-adjacent residues	38 – 39	2
	Non-terminal residue	62	1

Sequences

	Sequence		Length	Mass (Da)
	P56729 [UniParc]. Last modified January 23, 2007. Version 2. Checksum: 7D4E3C6AFC5AFB8B	FASTA	62	6,893
	10 20 30 40 50 60 MARKKFSGLE IXLIVLFAIV LSIAIALVVV XASKXPAVIK LPSDPIPTLR MEMTYHTDYM LE

References

[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.

Cross-references

Sequence databases
PIR	A25987.
3D structure databases
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Family and domain databases
InterPro	IPR000322. Glyco_hydro_31. [Graphical view]
PANTHER	PTHR22762. PTHR22762. 1 hit.
ProtoNet	Search...

Entry information

Entry name

SUIS_PIG

Accession

Primary (citable) accession number: P56729

Entry history

Integrated into UniProtKB/Swiss-Prot:	May 30, 2000
Last sequence update:	January 23, 2007
Last modified:	April 3, 2013
This is version 58 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Chordata Protein Annotation Program