Methionine adenosyltransferase (MAT; EC 2.5.1.6) catalyzes the biosynthesis of S-adenosylmethionine (AdoMet) from methionine and ATP. MAT II is a broadly expressed MAT consisting of catalytic alpha and noncatalytic beta subunits encoded by MAT2A) and MAT2B, respectively.LeGros et al. (2000) designed degenerate PCR primers to tryptic peptide sequence of MAT2B purified from human lymphocytes. They amplified a partial cDNA from Jurkat cells and extended the cDNA using 3-prime and 5-prime RACE. A full-length MAT2B cDNA amplified from normal human peripheral blood mononuclear cell RNA encodes a 334-amino acid protein with a molecular mass of 38 kD.