CONSERVATION OF FUNCTIONALLY IMPORTANT EPITOPES ON MYELIN-ASSOCIATED GLYCOPROTEIN (MAG)

Phylogenetic conservation of protein domains often points to functiona lly important regions, As a step toward mapping these sites on myelin associated glycoprotein (MAG) we have determined the species distribut ion of epitopes recognized by a panel of anti-MAG antibodies (Ab), Mon oclonal antibodies (mAb) B11F7, GenS3 and 28 recognized MAG only in ma mmalian species, However, the mAb 513 which inhibits MAG binding recog nized a conformational epitope in a wider distribution of species incl uding, human (Homo sapiens), bovine (Bos taurus), rat (Rattus norvegic us), chicken (Gallus gallus), quail (Coturnix coturnix japonica), liza rd (Iguana iguana), snake (Thamnophis sirtalis), frog (Xenopus laevis) acid turtle (all tetrapods) but not in goldfish (Crassius aurata) (a teleost), However, only MAG from mammals was shown to bind rat dorsal ganglion neurons (DRGs) suggesting that structures additional to those recognized by mAb 513 must be involved in function, Antibody 28, on t he other hand, recognized only MAG species which bound to neurons, sug gesting that this epitope, in comparison with mAb 513, more closely re presented the functionally important region of MAG, Observed species d ifferences in glycosylation of MAG may be functionally significant, A newly developed polyclonal Ab against MAG recognized the protein in te trapods and teleosts, but not chondricthyes. The results show that MAG is present in a wide spectrum of species.