A developmentally regulated chicken neuronal protein associated with the cortical cytoskeleton

Monoclonal antibody 3D5 recognizes a single component of the neuronal membrane skeleton isolated from the chicken embryo brain. The 3D5 antigen is highly enriched in the CNS, and smaller amounts are found in the PNS. It is also present in non-neural tissues, but this is due to peripheral innervation. The biochemical and molecular properties of the 3D5 antigen are very similar to those of the previously described mammalian protein B-50 (Zwiers et al., 1985)/GAP 43 (Jacobson et al., 1986)/pp46 (Ellis et al., 1985)/F1 (Chan et al., 1986), and include anomalous SDS gel migration, acidic isoelectric point, and extraction from the cytoplasmic side of the plasma membrane only under extremely alkaline conditions. The 3D5 antigen is also developmentally regulated, with maximum expression in brain occurring at E14-E16, after which levels decrease approximately 4-fold in the adult. Immunofluorescence staining of cultured neurons shows that the 3D5 antigen is located in all parts of the cell but is particularly enriched in the growth cone and the growth cone filopodia. As the 3D5 antigen is enriched in the membrane skeleton, we suggest that this protein is involved in an association between the actin-containing cytoskeleton and the plasma membrane.