lactase

Also known as LCT, lactase-glycosylceramidase, lactase-phlorizin hydrolase-1, lactase-phlorizin hydrolase

Key facts

Enzyme.Name: Glycosylceramidase(Phlorizin hydrolase)
Enzyme.EC_number: 3.2.1.62
Enzyme.CAS_number: 9033-10-7
Enzyme.GO_code: 0017042
Enzyme.image: 1jyn.jpg
Enzyme.width: 270
Enzyme.caption: E. coli lactase tetramer.
Protein.Name: Lactase
Protein.Symbol: LCT
Protein.AltSymbols: LAC; LPH; LPH1
Protein.HGNCid: 6530
Protein.Chromosome: 2
Protein.Arm: q
Protein.Band: 21
Protein.ECnumber: 3.2.1.108
Protein.OMIM: 603202
Protein.EntrezGene: 3938
Protein.RefSeq: NM_002299

via Wikipedia infobox

Protein · UniProt

Lactase/phlorizin hydrolase

Gene: LCT
Organism: Homo sapiens (Human)
Length: 1,927 aa
Molecular mass: 218,587 Da
Evidence: 1: Evidence at protein level

Broad specificity glycosidase of the intestinal brush border membrane that hydrolyzes lactose, the main sugar in mammalian milk, to produce D-glucose and D-galactose (PubMed:12594539, PubMed:16400612, PubMed:3929764, PubMed:9762914). The mature protein is composed of two domains that catalyze the hydrolysis of beta-glucopyranosides and beta-galactopyranosides, with a preference for hydrophilic aglycones (in lactose and cellobiose) for one domain and hydrophobic aglycones (in phlorizin and glycosylceramides) for the other (PubMed:12594539, PubMed:3929764, PubMed:9762914)

Cell membraneDisease variantGlycoproteinGlycosidaseHydrolaseMembraneMultifunctional enzymeProteomics identification

View on UniProt →

Swiss-Prot (reviewed) · via UniProt

Wikidata facts

Instance of: protein
Image: 1jyn.jpg

Show 4 more facts

Commons category: Lactase
EC enzyme number: 3.2.1.108
found in taxon: Homo sapiens
biological process: carbohydrate metabolic process

Sources (6)

via Wikidata · CC0

~10 min read

Encyclopedic overview

12 sections

Contents

The animal (including human) versions
Structure and biosynthesis
Genetic expression and regulation
Mechanism
Non-animal lactases and their uses
Added to food
Ingested
Biotechnology
See also
Notes
References
External links

Lactase () is an enzyme produced by many organisms and is essential to the complete digestion of whole milk. It breaks down the sugar lactose into its component parts, galactose and glucose, simple sugars that can be absorbed into the bloodstream through an animal's intestines. A lactase is a type of β-galactosidase because it breaks down the β-glycosidic bond in D-lactose. The chemical reaction it catalyzes is: C12H22O11 + H2O → C6H12O6 + C6H12O6 + heat. lactose + H2O → β-D-galactose + D-glucose

The only human gene encoding a lactase is LCT or lactase-phlorizin hydrolase (alternative symbol LPH). LCT has a lactase domain and a phlorizin hydrolase domain. It is encoded on chromosome 2. Lactase is found in the brush border of the small intestine of humans and other mammals. People without the mutation allowing production of functional LCT to continue past infancy may experience the symptoms of lactose intolerance after consuming milk products.

Excerpted from Wikipedia’s “lactase” article, available under the CC BY-SA 4.0 licence.