Defective LCT does not hydrolyze Lac

Stable Identifier
Reaction [transition]
Homo sapiens
Locations in the PathwayBrowser
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout

Mutations that disrupt the catalytic activity of LCT (lactase) block the cleavage of lactose (Lac) to galactose and glucose in the gut lumen and cause lactose intolerance in nursing infants. Affected individuals can develop severe diarrhea; the disease can be effectively managed by complete exclusion of lactose from the diet. A variety of LCT mutant alleles have been described. Two missense mutations that are associated with severe loss of lactase activity in vivo are annotated here (Kuokkanen et al. 2006; Torniainen et al. 2009).

Literature References
PubMed ID Title Journal Year
19161632 Four novel mutations in the lactase gene (LCT) underlying congenital lactase deficiency (CLD)

Catassi, C, Savilahti, E, Routi, T, Torniainen, S, Freddara, R, Gijsbers, C, Järvelä, I, Höglund, P

BMC Gastroenterol 2009
16400612 Mutations in the translated region of the lactase gene (LCT) underlie congenital lactase deficiency

Peltonen, Leena, Komu, H, Varilo, T, Savilahti, E, Enattah, NS, Kokkonen, J, Kuokkanen, M, Järvelä, I, Ylisaukko-Oja, T

Am. J. Hum. Genet. 2006
Catalyst Activity

lactase activity of LCT mutant dimers [plasma membrane]

Normal reaction
Functional status

Loss of function of LCT mutant dimers [plasma membrane]

Name Identifier Synonyms
lactose intolerance DOID:10604 LM - Lactose malabsorption
Cite Us!