ID   MMT1_HORVU              Reviewed;        1088 AA.
AC   Q9MBC2;
DT   19-JUL-2004, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2000, sequence version 1.
DT   03-AUG-2022, entry version 87.
DE   RecName: Full=Methionine S-methyltransferase;
DE            EC=2.1.1.12;
DE   AltName: Full=AdoMet:Met S-methyltransferase;
DE   AltName: Full=Hv-MMT1;
GN   Name=MMT1; Synonyms=MMT;
OS   Hordeum vulgare (Barley).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; Liliopsida; Poales; Poaceae; BOP clade;
OC   Pooideae; Triticodae; Triticeae; Hordeinae; Hordeum.
OX   NCBI_TaxID=4513;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   STRAIN=cv. Haruna Nijo;
RA   Pimenta M., Kaneta T., Kamiya Y.;
RT   "Cloning and expression studies of S-adenosyl-L-methionine:L-methionine S-
RT   methyltransferase (MMT) in germinating barley.";
RL   Submitted (JUN-1999) to the EMBL/GenBank/DDBJ databases.
RN   [2]
RP   PROTEIN SEQUENCE OF 159-183, ENZYME ACTIVITY, AND TISSUE SPECIFICITY.
RX   PubMed=9765528; DOI=10.1104/pp.118.2.431;
RA   Pimenta M.J., Kaneta T., Larondelle Y., Dohmae N., Kamiya Y.;
RT   "S-adenosyl-L-methionine:L-methionine S-methyltransferase from germinating
RT   barley. Purification and localization.";
RL   Plant Physiol. 118:431-438(1998).
CC   -!- FUNCTION: Catalyzes the S-methylmethionine (SMM) biosynthesis from
CC       adenosyl-L-homocysteine (AdoMet) and methionine. SMM biosynthesis (by
CC       MMT1) and degradation (by HMT-1, HMT-2 and HMT-3) constitute the SMM
CC       cycle in plants, which is probably required to achieve short term
CC       control of AdoMet level. Also able to catalyze the selenium-
CC       methylmethionine (SeMM) from AdoMet and selenium-methionine (SeMet).
CC       May play a role in phoem sulfur transport; such function is however not
CC       essential.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=L-methionine + S-adenosyl-L-methionine = S-adenosyl-L-
CC         homocysteine + S-methyl-L-methionine; Xref=Rhea:RHEA:13761,
CC         ChEBI:CHEBI:57844, ChEBI:CHEBI:57856, ChEBI:CHEBI:58252,
CC         ChEBI:CHEBI:59789; EC=2.1.1.12;
CC         Evidence={ECO:0000269|PubMed:9765528};
CC   -!- SUBUNIT: Homotetramer. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Expressed in the shoot, scutellum, and aleurone
CC       cells but not in the root or endosperm. {ECO:0000269|PubMed:9765528}.
CC   -!- DEVELOPMENTAL STAGE: Increases during germination.
CC   -!- SIMILARITY: Belongs to the class I-like SAM-binding methyltransferase
CC       superfamily. {ECO:0000305}.
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DR   EMBL; AB028870; BAA94795.1; -; mRNA.
DR   AlphaFoldDB; Q9MBC2; -.
DR   SMR; Q9MBC2; -.
DR   ExpressionAtlas; Q9MBC2; baseline and differential.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0030732; F:methionine S-methyltransferase activity; IEA:UniProtKB-EC.
DR   GO; GO:0030170; F:pyridoxal phosphate binding; IEA:InterPro.
DR   GO; GO:0009058; P:biosynthetic process; IEA:InterPro.
DR   GO; GO:0032259; P:methylation; IEA:UniProtKB-KW.
DR   GO; GO:0006807; P:nitrogen compound metabolic process; IEA:UniProt.
DR   GO; GO:0071704; P:organic substance metabolic process; IEA:UniProt.
DR   Gene3D; 3.40.50.150; -; 1.
DR   Gene3D; 3.40.640.10; -; 1.
DR   Gene3D; 3.90.1150.10; -; 1.
DR   InterPro; IPR004839; Aminotransferase_I/II.
DR   InterPro; IPR025779; Met_S-MeTrfase.
DR   InterPro; IPR015424; PyrdxlP-dep_Trfase.
DR   InterPro; IPR015421; PyrdxlP-dep_Trfase_major.
DR   InterPro; IPR015422; PyrdxlP-dep_Trfase_small.
DR   InterPro; IPR029063; SAM-dependent_MTases_sf.
DR   InterPro; IPR007848; Small_mtfrase_dom.
DR   Pfam; PF00155; Aminotran_1_2; 1.
DR   Pfam; PF05175; MTS; 1.
DR   SUPFAM; SSF53335; SSF53335; 1.
DR   SUPFAM; SSF53383; SSF53383; 2.
DR   PROSITE; PS51555; SAM_MT12; 1.
PE   1: Evidence at protein level;
KW   Cytoplasm; Direct protein sequencing; Methyltransferase;
KW   S-adenosyl-L-methionine; Transferase.
FT   CHAIN           1..1088
FT                   /note="Methionine S-methyltransferase"
FT                   /id="PRO_0000204461"
SQ   SEQUENCE   1088 AA;  119881 MW;  F1CB112F456C050B CRC64;
     MAAAAGDVEA FLAACQASGD AAYGAAKAVL ERLEAPATRA EARRLLGAVR RRFAAGGPAA
     GLECFRTFHF RIHDVVLDPH LQGFQQRKKL TMMEIPSIFI PEDWSFTFYE GLNRHPDSIF
     RDKTVAELGC GNGWISIALA EKWCPSKVYG LDINPRPIKI AWINLYLNAL DDDGLPIYDA
     EGKTLLDRVE FYESDLLSYC RDNKIELDRI VGCIPQILNP NPEAMSKIVT ENSSEEFLYS
     LSNYCALQGF VEDQFGLGLI ARAVEEGISV IKPSGLMVFN MGGRPGQGVC ERLFLRRGFR
     INKLWQTKIM QAADTDISAL VEIEKNSRHR FEFFMDLVGD QPVCARTAWA YMKSGGRISH
     ALSVYSCQLR QPNQVKKIFE FLKDGFHEVS SSLDLSFDDD SVADEKIPFL AYLASFLQEN
     KSNPCEPPAG CLNFRNLVAG FMKSYHHIPL TPDNVVVFPS RAVAIENALR LFSPGLAIVD
     EHLTRHLPKQ WLTSLAIEES NHAKDTVTVI EAPRQSDLLI ELIRKLKPQV VVTGMAQFEA
     ITSAAFVNLL SVTKDVGSRL LLDISEHLEL SSLPSSNGVL KYLAGKTLPS HAAILCGLVK
     NQVYSDLEVA FAISEDPTVY KALSQTIELL EGHTSVISQH YYGCLFHELL AFQIGDRHPQ
     QEREPAEVIS KEMIGFSSSA MSTLEGAEFF VPGSMESGVI HMDLDRSFLP VPSAVNASIF
     ESFVRQNITD SETDVRSSIQ QLVKDSYGFS AGGASEIIYG NTCLALFNKL VLCCMQEQGT
     LLFPLGTNGH YVNAAKFVNA TTLTIPTKAD SGFKIEPSAL ADTLEKVSQP WVYISGPTIN
     PTGFLYSDDD IAELLSVCAT YGARVVIDTS SSGLEFQATG CSQWNLERCL SNVKSSKPSF
     SVVLLGELSF ELTTAGLDFG FLIMSDSSLV DTFYSFPSLS RPHSTLKYTF RKLLGLKNQK
     DQHFSDLILE QKETLKNRAD QLIKMLESCG WDAVGCHGGI SMLAKPTAYI GKSLKVDGFE
     GKLDSHNMRE ALLRSTGLCI SSSGWTGVPD YCRFSFALES GDFDRAMECI ARFRELVLGG
     GAKVNGSN