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).
History
EC 2.4.1.22 created 1965
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)
MCF: 
102115300(B4GALT2) 102131044(B4GALT1) 102146034(LALBA)
MMU: 
14595(B4galt1) 16770(Lalba) 53418(B4galt2)
RNO: 
24390(B4galt1) 24528(Lalba) 313536(B4galt2)
CGE: 
100689430(Beta4galt-1) 100689434(B4galt2) 100758724
HGL: 
101701591(Lalba) 101718811(B4galt2) 101721414(B4galt1)
TUP: 
102470655(B4GALT1) 102483661 102489782(B4GALT2)
CFA: 
403730(LALBA) 481579(B4GALT1) 482527(B4GALT2)
AML: 
100471634(B4GALT2) 100477164(B4GALT1) 100478355
FCA: 
101084809(B4GALT2) 101090027(LALBA) 101100927(B4GALT1)
PTG: 
102955088(B4GALT2) 102959538(B4GALT1) 102972113
BTA: 
100125390(B4GALT2) 281781(B4GALT1) 281894(LALBA)
BOM: 
102269762(B4GALT1) 102283249(B4GALT2) 102287905(LALBA)
PHD: 
102317609(B4GALT2) 102321948(B4GALT1) 102342777(LALBA)
CHX: 
100860779(LALBA) 100860927(B4GALT1) 102191101(B4GALT2)
SSC: 
100511655(B4GALT1) 100736821(B4GALT2) 397647(LALBA)
CFR: 
102516080(B4GALT2) 102517623(B4GALT1) 102518569(LALBA)
ECB: 
100066149(B4GALT2) 100068209(B4GALT1) 100146585
MYB: 
102240062(B4GALT1) 102248727(B4GALT2) 102251448(LALBA)
MYD: 
102751484(B4GALT1) 102768578(LALBA) 102774860(B4GALT2)
PALE: 
102878748(B4GALT1) 102884318(B4GALT2) 102892277(LALBA)
MDO: 
100010600(B4GALT1) 100024086(LALBA) 100617718(B4GALT2)
SHR: 
OAA: 
100092000(B4GALT2)
GGA: 
396121(B4GALT1) 396122(B4GALT2)
MGP: 
TGU: 
100223650(B4GALT1) 100230857(B4GALT2)
FAB: 
101805871(B4GALT2) 101807052(B4GALT1)
PHI: 
102106294(B4GALT2) 102109081(B4GALT1)
APLA: 
101792817(B4GALT1) 101802590(B4GALT2)
FPG: 
101916596(B4GALT2) 101918852(B4GALT1)
FCH: 
102046112(B4GALT1) 102056545(B4GALT2)
CLV: 
102088289(B4GALT1) 102088677(B4GALT2)
ASN: 
102372956(B4GALT1) 102376584(B4GALT2)
PSS: 
102459690(B4GALT1)
CMY: 
102941864(B4GALT2) 102942662(B4GALT1)
ACS: 
XLA: 
100190782(b4galt2)
XTR: 
100145518(b4galt1.1) 100492356(b4galt2) 549418(b4galt1.2)
DRE: 
TRU: 
MZE: 
OLA: 
XMA: 
LCM: 
BFO: 
CIN: 
PHU: 
ISC: 
 » 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, Bos taurus, 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
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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