MAG
Description
The MAG (myelin associated glycoprotein) is a protein-coding gene located on chromosome 19.
Mag, MAG, Mags or mags may refer to:
MAG, also known as Siglec-4a, is a crucial adhesion molecule that facilitates communication between myelinating cells and neurons. It accomplishes this by binding to neuronal gangliosides, which contain sialic acid, and to the glycoproteins RTN4R and RTN4RL2. While not essential for the initial formation of myelin, MAG plays a vital role in maintaining the integrity of myelin sheaths surrounding axons. This protein acts as a protective agent for motoneurons, shielding them from programmed cell death (apoptosis), particularly after injury. This protective function is likely achieved through its interaction with neuronal RTN4R and RTN4RL2. In adult organisms, MAG is indispensable for preventing the degeneration of myelinated axons. This crucial function is believed to be dependent on its binding to gangliosides present on the axon's cell membrane. Furthermore, MAG acts as a negative regulator of neurite outgrowth. Its inhibitory effects on neurite extension vary depending on the type of neuron. In dorsal root ganglion neurons, the inhibition is primarily mediated by MAG's binding to neuronal RTN4R or RTN4RL2, with a lesser contribution from binding to neuronal gangliosides. In cerebellar granule cells, the inhibitory effect is primarily driven by MAG's interaction with neuronal gangliosides. In sensory neurons, the inhibition of neurite extension relies only partially on RTN4R, RTN4RL2, and gangliosides. MAG also inhibits the longitudinal growth of axons, likely through its interaction with RTN4R. Its binding preference leans towards alpha-2,3-linked sialic acid, and it has been shown to bind to the ganglioside Gt1b. MAG exists as both a monomer and a homodimer. The interaction with RTN4R and RTN4RL2 is facilitated by the first three N-terminal Ig-like domains of MAG. Notably, MAG has been shown to interact with RTN4R and with isoform 2 of BSG.
MAG is also known as GMA, S-MAG, SIGLEC-4A, SIGLEC4, SIGLEC4A, SPG75.
