KEGG   ENZYME: 2.4.1.22Help
Entry
EC 2.4.1.22                 Enzyme                                 
Name
lactose synthase;
UDP-galactose---glucose galactosyltransferase;
N-acetyllactosamine synthase;
uridine diphosphogalactose-glucose galactosyltransferase;
lactose synthetase;
UDP-galactose:D-glucose 4-beta-D-galactotransferase;
UDP-galactose:D-glucose 4-beta-D-galactosyltransferase
Class
Transferases;
Glycosyltransferases;
Hexosyltransferases
BRITE hierarchy
Sysname
UDP-alpha-D-galactose:D-glucose 4-beta-D-galactosyltransferase
Reaction(IUBMB)
UDP-alpha-D-galactose + D-glucose = UDP + lactose [RN:R00503 R06067]
Reaction(KEGG)
Substrate
UDP-alpha-D-galactose [CPD:C00052];
D-glucose [CPD:C00031]
Product
UDP [CPD:C00015];
lactose [CPD:C00243]
Comment
The enzyme is a complex of two proteins, A and B. In the absence of the B protein (alpha-lactalbumin), the enzyme catalyses the transfer of galactose from UDP-alpha-D-galactose to N-acetylglucosamine (EC 2.4.1.90 N-acetyllactosamine synthase).
Pathway
Galactose metabolism
Metabolic pathways
Orthology
K00704  
alpha-lactalbumin
K07966  
beta-1,4-galactosyltransferase 1
K07967  
beta-1,4-galactosyltransferase 2
Genes
HSA: 
2683(B4GALT1) 3906(LALBA) 8704(B4GALT2)
PTR: 
100613700(B4GALT1) 456522(B4GALT2) 743291(LALBA)
PPS: 
100974756(B4GALT1) 100980267(B4GALT2) 100989301(LALBA)
GGO: 
101133326(B4GALT2) 101138539(LALBA) 101138982(B4GALT1)
PON: 
100437438(LALBA) 100437696(B4GALT2) 100438031(B4GALT1)
MCC: 
703541(B4GALT1) 704038(B4GALT2) 707442(LALBA)
MMU: 
14595(B4galt1) 16770(Lalba) 53418(B4galt2)
RNO: 
24390(B4galt1) 24528(Lalba) 313536(B4galt2)
CFA: 
403730(LALBA) 481579(B4GALT1) 482527(B4GALT2)
AML: 
100471634(B4GALT2) 100477164(B4GALT1) 100478355
FCA: 
101084809(B4GALT2) 101090027(LALBA) 101100927
BTA: 
100125390(B4GALT2) 281781(B4GALT1) 281894(LALBA)
SSC: 
100511655(B4GALT1) 397647(LALBA)
ECB: 
100066149(B4GALT2) 100068209 100146585
MDO: 
100010600 100024086 100617718
SHR: 
100918732(B4GALT2) 100929465 100931076
OAA: 
100092000
GGA: 
396121(B4GALT1) 396122(B4GALT2)
MGP: 
100543545
TGU: 
100223650(B4GALT1) 100230857(B4GALT2)
ACS: 
100557558 100561064
XLA: 
100190782(b4galt2)
XTR: 
100145518(b4galt1.1) 100492356 549418(b4galt1.2)
DRE: 
100148828 550425(b4galt1) 768123
TRU: 
101066088 101072068
OLA: 
100301598(b4gal-t2) 101171148
CIN: 
100175041
 » show all
Taxonomy
Reference
1  [PMID:5440844]
  Authors
Fitzgerald DK, Brodbeck U, Kiyosawa I, Mawal R, Colvin B, Ebner KE.
  Title
Alpha-lactalbumin and the lactose synthetase reaction.
  Journal
J. Biol. Chem. 245 (1970) 2103-8.
  Organism
Rattus norvegicus [GN:rno], Bos taurus [GN:bta], Cavia porcellus
Reference
2  [PMID:812340]
  Authors
Hill RL, Brew K.
  Title
Lactose synthetase.
  Journal
Adv. Enzymol. Relat. Areas. Mol. Biol. 43 (1975) 411-90.
Reference
3  [PMID:14005251]
  Authors
WATKINS WM, HASSID WZ.
  Title
The synthesis of lactose by particulate enzyme preparations from guinea pig and bovine mammary glands.
  Journal
J. Biol. Chem. 237 (1962) 1432-40.
  Organism
Cavia porcellus, Bos taurus [GN:bta]
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
9030-11-9
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