Myelin-associated glycoprotein (MAG) is a cell membrane glycoprotein that is a member of the SIGLEC family of proteins and is a functional ligand of the NOGO-66 receptor, NgR MAG is believed to be involved in myelination during nerve regeneration.Myelin-associated glycoprotein (MAG), a membrane protein of 100 kD, is thought to be involved in the process of myelination (Barton et al., 1987). MAG is a sialic acid-binding SIGLEC protein and is a functional ligand for the NOGO receptor (NGR, or RTN4R) (Liu et al., 2002).Spagnol et al. (1989) found that MAG cDNA clones isolated from a human brain cDNA library had an open reading frame of 1,878 nucleotides encoding a peptide of 626 amino acids with a calculated molecular weight of 69.1 kD.