DB code: S00046

RLCP classification 3.105.250000.90 : Transfer
CATH domain : Methane Monooxygenase Hydroxylase; Chain G, domain 1 Catalytic domain
E.C. 2.7.1.-
CSA 1e2a
M-CSA 1e2a

CATH domain Related DB codes (homologues)

Uniprot Enzyme Name
UniprotKB Protein name Synonyms RefSeq Pfam
P23532 Lactose-specific phosphotransferase enzyme IIA component
EC 2.7.1.-
PTS system lactose-specific EIIA component
YP_004761516.1 (Protein)
NC_015862.1 (DNA/RNA sequence)
PF02255 (PTS_IIA)
[Graphical View]

KEGG enzyme name

UniprotKB: Accession Number Entry name Activity Subunit Subcellular location Cofactor
P23532 PTLA_LACLA Protein EIIA N(pi)-phospho-L-histidine + protein EIIB = protein EIIA + protein EIIB N(pi)-phospho-L- histidine/cysteine. Homotrimer. Cytoplasm. Binds 1 magnesium ion per trimer.

KEGG Pathways
Map code Pathways E.C.

Compound table
Substrates Products Intermediates
KEGG-id C04261 C02743 C00615 L00031
Compound Protein N(pi)-phospho-L-histidine Protein cysteine Protein histidine Protein S-phosphoryl-cysteine
Type aromatic ring (with nitrogen atoms),peptide/protein,phosphate group/phosphate ion peptide/protein,sulfhydryl group aromatic ring (with nitrogen atoms),peptide/protein peptide/protein,phosphate group/phosphate ion,sulfide group
1e2aA Unbound Unbound Unbound Unbound
1e2aB Unbound Unbound Unbound Unbound
1e2aC Unbound Unbound Unbound Unbound

Reference for Active-site residues
resource references E.C.
Swiss-prot;P23532 & Catalytic Site Atlas

Active-site residues
PDB Catalytic residues Cofactor-binding residues Modified residues Main-chain involved in catalysis Comment
1e2aA HIS 54;HIS 78;GLN 80;ASP 81;HIS 82 HIS 78(phosphorylated)
1e2aB HIS 54;HIS 78;GLN 80;ASP 81;HIS 82 HIS 78(phosphorylated)
1e2aC HIS 54;HIS 78;GLN 80;ASP 81;HIS 82 HIS 78(phosphorylated)

References for Catalytic Mechanism
References Sections No. of steps in catalysis

Medline ID
PubMed ID 9261069
Journal Structure
Year 1997
Volume 5
Pages 775-88
Authors Sliz P, Engelmann R, Hengstenberg W, Pai EF
Title The structure of enzyme IIAlactose from Lactococcus lactis reveals a new fold and points to possible interactions of a multicomponent system.
Related PDB 1e2a
Related UniProtKB P23532

This Enzyme is involved in PTS system, to which the other phosphoryl transferases (S00297, D00527, D00525, S00283, S00420 in EzCatDB) also belong. Many of such enzymes have got the same E.C. number ( This enzyme also had the same E.C. number previously, which was changed to 2.7.1.-.
Moreover, this enzyme seems to transfer the phosphoryl group from His residue of Phosphocarrier protein HPr (Swiss-prot;Q9CJ83) to Cys residue of the PTS system lactose-specific EIIB component (Swiss-prot;P23531), which is homologous to the counterpart enzyme from E. coli (D00525 in EzCatDB).
His78 is the active site, which is phosphorylated by phosphorylcarrier protein, HPr. The NE atom of His78 must be deprotonated at physiolosical pH [1]. And then, this enzyme phosphorylates IIBlactose domain in PTS system (cf. D00525).

Created Updated
2002-08-01 2009-02-26