Phosphorylation of the neural cell adhesion molecule on serine or threonine residues is induced by adhesion or nerve growth factor

The neural cell adhesion molecule (NCAM) is a member of the immunoglobulin superfamily and plays a crucial role during development and regeneration. It is expressed in three major isoforms; two of them with intracellular domains of different length and one without any intracellular domain. NCAM is known to be phosphorylated and contains up to 49 serine or threonine residues, which could be phosphorylated. However, the impact of NCAM phosphorylation is still unclear. Here we describe NCAM being phosphorylated during neuronal differentiation of PC12 cells. We provide evidence that protein kinase C is involved in the phosphorylation of NCAM. In agreement with our earlier observation that the protein phosphatase 1 is associated with NCAM, we additionally found that NCAM is a substrate for the protein phosphatase 1 but not for the protein phosphatase 2A.