Reviewed, UniProtKB/Swiss-Prot Q42653 (OMT2_CHRAE)

Names and origin

Protein names

Recommended name:
    Quercetin 3-O-methyltransferase 2
    EC=2.1.1.76
Alternative name(s):
    Flavonol 3-O-methyltransferase 2

Gene names

Name:

OMT2

Organism

Chrysosplenium americanum (Golden saxifrage)

Taxonomic identifier

36749 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › Saxifragales › Saxifragaceae › Chrysosplenium

Protein attributes

Sequence length	343 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Methylates OH residues of flavonoid and phenylpropanoid compounds and shows a higher affinity for flavonoid than phenylpropanoid substrates. Substrate preference is quercetin (flavonoid) = luteolin (flavonoid) = 5-hydroxyferulic acid (phenylpropanoid) > caffeic acid (phenylpropanoid) >> apigenin (flavonoid) = kempferol (flavonoid). 3,4-dimethylquercetin is not a substrate.
Catalytic activity	S-adenosyl-L-methionine + 3,5,7,3',4'-pentahydroxyflavone = S-adenosyl-L-homocysteine + 3-methoxy-5,7,3',4'-tetrahydroxyflavone.
Pathway	Flavonoid metabolism; quercetin degradation.
Subunit structure	Homodimer By similarity.
Sequence similarities	Belongs to the methyltransferase superfamily. Type 2 family. COMT subfamily.
Caution	It is not sure if OMT1 and OMT2 are really encoded by two different genes or if they represent cloning artifacts.
biophysicochemical properties	Kinetic parameters: The Vmax value for flavonoid compounds methylation is two to threefold lower for OMT2 than for OMT1.

Ontologies

Keywords
Ligand	S-adenosyl-L-methionine
Molecular function	Methyltransferase Transferase
Gene Ontology (GO)
Molecular function	O-methyltransferase activity Inferred from electronic annotation. Source: InterPro protein dimerization activity Inferred from electronic annotation. Source: InterPro quercetin 3-O-methyltransferase activity Inferred from electronic annotation. Source: EC
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 343	343	Quercetin 3-O-methyltransferase 2		PRO_0000063216
Sites
	Active site	245	1	Proton acceptor By similarity
	Binding site	184	1	S-adenosyl-L-methionine; via carbonyl oxygen By similarity
	Binding site	207	1	S-adenosyl-L-methionine By similarity
	Binding site	227	1	S-adenosyl-L-methionine By similarity
	Binding site	228	1	S-adenosyl-L-methionine; via amide nitrogen By similarity
	Binding site	241	1	S-adenosyl-L-methionine By similarity

Sequences

	Sequence		Length	Mass (Da)
	Q42653-1 [UniParc]. Last modified November 1, 1996. Version 1. Checksum: 8D363A98330FDE4F	FASTA	343	37,868
	10 20 30 40 50 60 MLFAMQLACA SVLPMVLKSA IELDLLEIIR GQDTCMSPTE IASHLPTTNP DAPAMVDRIL 70 80 90 100 110 120 RLLSCYSVVT CSVRSVDDQR VYGLAPVCKY LTKNQDGVSI AALCLMNQDK VLMESWYHLK 130 140 150 160 170 180 DAVLDGGIPF NKAYGMSSFE YHGTDPRFNK VFNRGMSDHS TITMKKVFQT YQGFQGLTSL 190 200 210 220 230 240 VDVGGGTGAT LTMILSKYPT IRCINFDLPH VIEDAPEYPG IEHVGGDMFV SVPKGDAIFM 250 260 270 280 290 300 KWICHDWSDE HCLKLLKNCY DALPNNGKVI LAECILPEVP DSSLATKGVV HIDVITVAHN 310 320 330 340 PGGKERTEKE FEALAKAAGF QGFQVFCNAF NTYIIEFSKK ICN

References

[1]

"Characterization of two cDNA clones which encode O-methyltransferases for the methylation of both flavonoid and phenylpropanoid compounds." Gauthier A., Gulick P.J., Ibrahim R.K. Arch. Biochem. Biophys. 351:243-249(1998) [PubMed: 9514654] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], CHARACTERIZATION. Tissue: Leaf.

Cross-references

Sequence databases
EMBLGenBankDDBJ	U16793 mRNA. Translation: AAA86982.1.
3D structure databases
HSSP	HSSP built from PDB template 1KYZ based on UniProtKB P28002.
SMR	Q42653. Positions 2-341.
ModBase	Search...
Enzyme and pathway databases
BRENDA	2.1.1.76. 262661.
Family and domain databases
InterPro	IPR016461. O-MeTrfase_COMT_euk. IPR001077. O_MeTrfase_2. IPR012967. Plant_MeTrfase_dimerisation. IPR011991. Wing_hlx_DNA_bd. [Graphical view]
Gene3D	G3DSA:1.10.10.10. Wing_hlx_DNA_bd. 1 hit.
Pfam	PF08100. Dimerisation. 1 hit. PF00891. Methyltransf_2. 1 hit. [Graphical view]
PIRSF	PIRSF005739. O-mtase. 1 hit.
ProtoNet	Search...

Entry information

Entry name

OMT2_CHRAE

Accession

Primary (citable) accession number: Q42653

Entry history

Integrated into UniProtKB/Swiss-Prot:	October 19, 2002
Last sequence update:	November 1, 1996
Last modified:	January 20, 2009
This is version 50 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

PPAP (Plant Proteome Annotation Project)