Reviewed, UniProtKB/Swiss-Prot Q8LAX0 (HMT3_ARATH)

Names and origin

Protein names

Recommended name:
    Homocysteine S-methyltransferase 3
    EC=2.1.1.10
Alternative name(s):
    S-methylmethionine:homocysteine methyltransferase 3
      Short name=SMM:Hcy S-methyltransferase 3
      Short name=AtHMT-3

Gene names

Name:	HMT3
Ordered Locus Names:	At3g22740
ORF Names:	MWI23.11

Organism

Arabidopsis thaliana (Mouse-ear cress) [Complete proteome]

Taxonomic identifier

3702 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › rosids › eurosids II › Brassicales › Brassicaceae › Arabidopsis

Protein attributes

Sequence length	347 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Catalyzes methyl transfer from S-methylmethionine (SMM) to adenosyl-L-homocysteine (AdoMet). SMM degradation (by HMT-1, HMT-2 and HMT-3) and biosynthesis (by MMT1) constitute the SMM cycle in plants, which is probably required to achieve short term control of AdoMet level. Ref.1
Catalytic activity	S-adenosyl-L-methionine + L-homocysteine = S-adenosyl-L-homocysteine + L-methionine. Ref.1
Cofactor	Zinc Potential.
Subunit structure	Monomer By similarity.
Tissue specificity	Expressed predominantly in rosette leaves. Expressed in roots, cauline leaves and developing seeds. Ref.1
Miscellaneous	In contrast to HMT-1, it is not inhibited by methionine.
Sequence similarities	Contains 1 Hcy-binding domain.
biophysicochemical properties	Kinetic parameters: KM=335 µM for S-methylmethionine KM=1760 µM for (S,S)-AdoMet

Ontologies

Keywords
Biological process	Amino-acid biosynthesis Methionine biosynthesis
Ligand	Metal-binding S-adenosyl-L-methionine Zinc
Molecular function	Methyltransferase Transferase
Technical term	Complete proteome
Gene Ontology (GO)
Biological process	methionine biosynthetic process Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	plasma membrane Inferred from direct assay. Source: TAIR
Molecular function	homocysteine S-methyltransferase activity Inferred from electronic annotation. Source: EC zinc ion binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 347	347	Homocysteine S-methyltransferase 3		PRO_0000114613
Regions
	Domain	12 – 333	322	Hcy-binding
Sites
	Metal binding	251	1	Zinc Potential
	Metal binding	318	1	Zinc Potential
	Metal binding	319	1	Zinc Potential
Experimental info
	Sequence conflict	24	1	A → E in AAM65096. Ref.5
	Sequence conflict	45	1	L → I in AAM65096. Ref.5
	Sequence conflict	117	1	C → W in AAM65096. Ref.5

Sequences

	Sequence		Length	Mass (Da)
	Q8LAX0-1 [UniParc]. Last modified July 19, 2004. Version 2. Checksum: 45CDC34973F820CC	FASTA	347	37,882
	10 20 30 40 50 60 MGSFVKEETS SLMTDFLEKC GGYAVVDGGF ATELQRHGAD INDPLWSAKC LITSPHLVTK 70 80 90 100 110 120 VHLDYLESGA NIIITASYQA TIQGFVAKGL SVGEAENLLR RSVEITYEAR EIFYNRCTKG 130 140 150 160 170 180 SWDFAYAGKA SRRPILVAAS VGSYGAYLAD GSEYSGIYGD SVSKETLKDF HRRRVQILAK 190 200 210 220 230 240 SGADLIAFET IPNKLEAEAY ADLLEEEDID IPAWFSFTSK DGVSVPRGDS VVECAKVADS 250 260 270 280 290 300 CKNVVAIGIN CTAPRYIHAL IISLRQMTRK PIVVYPNSGE VYDGLNKKWI KSEGESEEDF 310 320 330 340 VSYVSKWRDA GASLFGGCCR TTPNTIRAIA KVLSDEPSAA SKPKFGQ

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"The S-methylmethionine cycle in angiosperms: ubiquity, antiquity and activity." Ranocha P., McNeil S.D., Ziemak M.J., Li C., Tarczynski M.C., Hanson A.D. Plant J. 25:575-584(2001) [PubMed: 11309147] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], ENZYME ACTIVITY, PROBABLE FUNCTION OF SMM CYCLE, BIOPHYSICOCHEMICAL PROPERTIES, TISSUE SPECIFICITY. Strain: cv. Columbia. Tissue: Leaf.
[2]	"Structural analysis of Arabidopsis thaliana chromosome 3. I. Sequence features of the regions of 4,504,864 bp covered by sixty P1 and TAC clones." Sato S., Nakamura Y., Kaneko T., Katoh T., Asamizu E., Tabata S. DNA Res. 7:131-135(2000) [PubMed: 10819329] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: cv. Columbia.
[3]	"Functional annotation of a full-length Arabidopsis cDNA collection." Seki M., Narusaka M., Kamiya A., Ishida J., Satou M., Sakurai T., Nakajima M., Enju A., Akiyama K., Oono Y., Muramatsu M., Hayashizaki Y., Kawai J., Carninci P., Itoh M., Ishii Y., Arakawa T., Shibata K., Shinagawa A., Shinozaki K. Science 296:141-145(2002) [PubMed: 11910074] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA]. Strain: cv. Columbia.
[4]	"Empirical analysis of transcriptional activity in the Arabidopsis genome." Yamada K., Lim J., Dale J.M., Chen H., Shinn P., Palm C.J., Southwick A.M., Wu H.C., Kim C.J., Nguyen M., Pham P.K., Cheuk R.F., Karlin-Newmann G., Liu S.X., Lam B., Sakano H., Wu T., Yu G. , Miranda M., Quach H.L., Tripp M., Chang C.H., Lee J.M., Toriumi M.J., Chan M.M., Tang C.C., Onodera C.S., Deng J.M., Akiyama K., Ansari Y., Arakawa T., Banh J., Banno F., Bowser L., Brooks S.Y., Carninci P., Chao Q., Choy N., Enju A., Goldsmith A.D., Gurjal M., Hansen N.F., Hayashizaki Y., Johnson-Hopson C., Hsuan V.W., Iida K., Karnes M., Khan S., Koesema E., Ishida J., Jiang P.X., Jones T., Kawai J., Kamiya A., Meyers C., Nakajima M., Narusaka M., Seki M., Sakurai T., Satou M., Tamse R., Vaysberg M., Wallender E.K., Wong C., Yamamura Y., Yuan S., Shinozaki K., Davis R.W., Theologis A., Ecker J.R. Science 302:842-846(2003) [PubMed: 14593172] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA]. Strain: cv. Columbia.
[5]	"Full-length cDNA from Arabidopsis thaliana." Brover V.V., Troukhan M.E., Alexandrov N.A., Lu Y.-P., Flavell R.B., Feldmann K.A. Submitted (MAR-2002) to the EMBL/GenBank/DDBJ databases Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].

Cross-references

Sequence databases
EMBLGenBankDDBJ	AF297394 mRNA. Translation: AAG10301.1. AB022223 Genomic DNA. Translation: BAB01249.1. AK118021 mRNA. Translation: BAC42654.1. BT005318 mRNA. Translation: AAO63382.1. AY087554 mRNA. Translation: AAM65096.1.
IPI	IPI00516296.
RefSeq	NP_566715.1.
UniGene	At.6305
3D structure databases
ModBase	Search...
Proteomic databases
PRIDE	Q8LAX0.
Genome annotation databases
GeneID	821845.
GenomeReviews	Gene locus AT3G22740 in contig BA000014_GR.
KEGG	ath:AT3G22740.
NMPDR	fig|3702.1.peg.14522.
Organism-specific databases
TAIR	At3g22740.
Phylogenomic databases
OMA	Q8LAX0. AWFSFTS.
Enzyme and pathway databases
BRENDA	2.1.1.10. 302.
Gene expression databases
ArrayExpress	Q8LAX0.
GermOnline	AT3G22740. Arabidopsis thaliana.
Family and domain databases
InterPro	IPR003726. S_MeTrfase. [Graphical view]
Gene3D	G3DSA:3.20.20.330. S_methyl_trans. 1 hit.
Pfam	PF02574. S-methyl_trans. 1 hit. [Graphical view]
PROSITE	PS50970. HCY. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

HMT3_ARATH

Accession

Primary (citable) accession number: Q8LAX0
Secondary accession number(s): Q9LUI7

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 19, 2004
Last sequence update:	July 19, 2004
Last modified:	June 16, 2009
This is version 41 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

PPAP (Plant Proteome Annotation Project)