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Abstract

Like most other cells, neurons possess a spectrin/actin based network closely associated with the inner side of the cell membrane, the cortical cytoskeleton. This structure serves many diverse functions during axonal outgrowth. In the growth cone, the cortical cytoskeleton is involved in surface shaping, modulation of integral membrane proteins, and signal transduction. We developed two strategies to prepare material enriched for neural cortical cytoskeleton. The first strategy combined the isolation of a membrane/cortical cytoskeleton fraction by density gradient centrifugation with an enzymatic degradation of cell surface proteins. The second strategy is based on the attachment and crosslinking of single cells to beads, allowing for the removal of the cell contents by cell disruption; only membrane/cortical cytoskeleton patches are retained on the beads. Both strategies made use of the intimate association of the cortical cytoskeleton with the cell membrane, permitting the removal of cytoplasm, organelles and cytoplasmic cytoskeleton while retaining the cortical cytoskeleton. Monoclonal antibodies generated using both preparations as immunization material were screened for recognition of intracellular structures in axons and growth cones of retinal ganglion cells in culture. A quantitative specification of the antibodies is presented and six antibodies are characterized in immunolabelings and Western blot analysis.