1,4-alpha-glucan-branching enzyme (glycogen-branching enzyme, brancher enzyme, GBE1)

Function

• required for sufficient glycogen accumulation
• alpha 1-6 branches of glycogen play an important role in increasing solubility of the molecule &, consequently, in diminishing osmotic pressure within cells
• glycan biosynthesis, glycogen biosynthesis
• transfers a segment of a 1,4-alpha-D-glucan chain to a primary hydroxy group in a similar glucan chain

Structure

belongs to the glycosyl hydrolase 13 family

Expression

highest levels found in liver & muscle

Pathology

• defects in GBE1 are the cause of glycogen storage disease type 4
• neuromuscular perinatal glycogen storage disease type 4
• defects in GBE1 are the cause of adult polyglucosan body disease

More general terms

• hexosyltransferase
• phosphoprotein

Database

• OMIM: https://mirror.omim.org/entry/232500
• OMIM: https://mirror.omim.org/entry/236750
• OMIM: https://mirror.omim.org/entry/263570
• OMIM: https://mirror.omim.org/entry/607839
• UniProt: http://www.uniprot.org/uniprot/Q04446.html