Catalyzes the formation of S-adenosylmethionine from methionine and ATP. The reaction comprises two steps that are both catalyzed by the same enzyme: formation of S-adenosylmethionine (AdoMet) and triphosphate, and subsequent hydrolysis of the triphosphate. MAT2A Protein, Human, Recombinant (E. coli, His) is expressed in E. coli expression system with C-6xHis tag. The predicted molecular weight is 44.8 kDa and the accession number is P31153.