1,4-alpha-glucan-branching enzyme
Domain
Binds its carbohydrate substrate close to the active site, but also via regions close to the N-terminus; this may result in increased affinity and therefore increased catalytic efficiency.
Function
Glycogen-branching enzyme participates in the glycogen biosynthetic process along with glycogenin and glycogen synthase. Generates alpha-1,6-glucosidic branches from alpha-1,4-linked glucose chains, to increase solubility of the glycogen polymer (PubMed:26199317, PubMed:8463281, PubMed:8613547).
Involvement in disease
Glycogen storage disease 4
GSD4
A metabolic disorder characterized by the accumulation of an amylopectin-like polysaccharide. The typical clinical manifestation is liver disease of childhood, progressing to lethal hepatic cirrhosis. Most children with this condition die before two years of age. However, the liver disease is not always progressive. No treatment apart from liver transplantation has been found to prevent progression of the disease. There is also a neuromuscular form of glycogen storage disease type 4 that varies in onset (perinatal, congenital, juvenile, or adult) and severity.
None
The disease is caused by variants affecting the gene represented in this entry.
Neuromuscular perinatal glycogen storage disease type 4 is associated with non-immune hydrops fetalis, a generalized edema of the fetus with fluid accumulation in the body cavities due to non-immune causes. Non-immune hydrops fetalis is not a diagnosis in itself but a symptom, a feature of many genetic disorders, and the end-stage of a wide variety of disorders.
Polyglucosan body neuropathy, adult form
APBN
A late-onset, slowly progressive disorder affecting the central and peripheral nervous systems. Patients typically present after age 40 years with a variable combination of cognitive impairment, pyramidal tetraparesis, peripheral neuropathy, and neurogenic bladder. Other manifestations include cerebellar dysfunction and extrapyramidal signs. The pathologic hallmark of APBN is the widespread accumulation of round, intracellular polyglucosan bodies throughout the nervous system, which are confined to neuronal and astrocytic processes.
None
The disease is caused by variants affecting the gene represented in this entry.
Pathway
Glycan biosynthesis; glycogen biosynthesis.
Sequence Similarities
Belongs to the glycosyl hydrolase 13 family. GlgB subfamily.
Alternative names
Brancher enzyme, Glycogen-branching enzyme, GBE1