N-methyltransferase that catalyzes the formation of anserine (beta-alanyl-N(Pi)-methyl-L-histidine) from carnosine. Anserine, a methylated derivative of carnosine (beta-alanyl-L-histidine), is an abundant constituent of vertebrate skeletal muscles. Also methylates other L-histidine-containing di- and tripeptides such as Gly-Gly-His, Gly-His and homocarnosine (GABA-His). carnosine + S-adenosyl-L-methionine = anserine + H(+) + S-adenosyl-L-homocysteine kcat is 0.09 min(-1) for carnosine. kcat is 3.57 min(-1) for S-adenosyl-L-methionine. Optimum pH is 7.0-7.5. Optimum temperature is 50 degrees Celsius. Homodimer. Each monomer accommodates one molecule of carnosine in its active pocket (residues 313-398), precisely anchoring the histidine imidazole ring such that only N1 is exposed and deprotonated for methylation. Expressed at higher level in kidney. Expressed at lower level in brain and skeletal muscle. The Gly-Xaa-Gly-Xaa-Gly (GXGXG) motif binds the adenosyl part of S-adenosyl-L-methionine. The carnosine-binding region forms hydrophobic and hydrogen bonds with carnosine, defining a flipping orientation of the imidazole ring so that N1 is present next to S-adenosyl-L-methionine for methylation. Belongs to the carnosine N-methyltransferase family. Truncated N-terminus.