Protein
Methionine S-methyltransferase
Function
Catalyzes the S-methylmethionine (SMM) biosynthesis from adenosyl-L-homocysteine (AdoMet) and methionine. SMM biosynthesis (by MMT1) and degradation (by HMT-1, HMT-2 and HMT-3) constitute the SMM cycle in plants, which is probably required to achieve short term control of AdoMet level. Also able to catalyze the selenium-methylmethionine (SeMM) from AdoMet and selenium-methionine (SeMet). May play a role in phoem sulfur transport; such function is however not essential.
Similarity
Belongs to the class I-like SAM-binding methyltransferase superfamily.
Sequence
MAAAAGDVEAFLAACQASGDAAYGAAKAVLERLEAPATRAEARRLLGAVRRRFAAGGPAAGLECFRTFHFRIHDVVLDPHLQGFQQRKKLTMMEIPSIFIPEDWSFTFYEGLNRHPDSIFRDKTVAELGCGNGWISIALAEKWCPSKVYGLDINPRPIKIAWINLYLNALDDDGLPIYDAEGKTLLDRVEFYESDLLSYCRDNKIELDRIVGCIPQILNPNPEAMSKIVTENSSEEFLYSLSNYCALQGFVEDQFGLGLIARAVEEGISVIKPSGLMVFNMGGRPGQGVCERLFLRRGFRINKLWQTKIMQAADTDISALVEIEKNSRHRFEFFMDLVGDQPVCARTAWAYMKSGGRISHALSVYSCQLRQPNQVKKIFEFLKDGFHEVSSSLDLSFDDDSVADEKIPFLAYLASFLQENKSNPCEPPAGCLNFRNLVAGFMKSYHHIPLTPDNVVVFPSRAVAIENALRLFSPGLAIVDEHLTRHLPKQWLTSLAIEESNHAKDTVTVIEAPRQSDLLIELIRKLKPQVVVTGMAQFEAITSAAFVNLLSVTKDVGSRLLLDISEHLELSSLPSSNGVLKYLAGKTLPSHAAILCGLVKNQVYSDLEVAFAISEDPTVYKALSQTIELLEGHTSVISQHYYGCLFHELLAFQIGDRHPQQEREPAEVISKEMIGFSSSAMSTLEGAEFFVPGSMESGVIHMDLDRSFLPVPSAVNASIFESFVRQNITDSETDVRSSIQQLVKDSYGFSAGGASEIIYGNTCLALFNKLVLCCMQEQGTLLFPLGTNGHYVNAAKFVNATTLTIPTKADSGFKIEPSALADTLEKVSQPWVYISGPTINPTGFLYSDDDIAELLSVCATYGARVVIDTSSSGLEFQATGCSQWNLERCLSNVKSSKPSFSVVLLGELSFELTTAGLDFGFLIMSDSSLVDTFYSFPSLSRPHSTLKYTFRKLLGLKNQKDQHFSDLILEQKETLKNRADQLIKMLESCGWDAVGCHGGISMLAKPTAYIGKSLKVDGFEGKLDSHNMREALLRSTGLCISSSGWTGVPDYCRFSFALESGDFDRAMECIARFRELVLGGGAKVNGSN