S100 beta inhibits the phosphorylation of the L-MAG cytoplasmic domain by PKA

The myelin-associated glycoprotein (MAG) is a cell adhesion molecule expres sed by myelinating glia, existing as two isoforms that differ only by their cytoplasmic domains. We have studied the in vitro phosphorylation of recom binant rat MAG cytoplasmic domains by three kinases for which consensus seq uences exist within this domain, revealing phosphorylation of the L-MAG-spe cific domain by protein kinase A (PKA). Phosphorylation of the L-MAG cytopl asmic domain by PKA was decreased in the presence of S100 beta, providing a functional significance to the interaction between L-MAG and S100 beta, an d further indicating that L-MAG may play a role in myelinating glial cell s ignalling processes. (C) 2000 Elsevier Science B.V. All rights reserved.