Can GAP-43 interact with brain spectrin?

The growth-associated and presynaptic protein GAP-43 is important for axona l growth during brain development, for synaptic plasticity and in axonal re generation [Benowitz, Routtenberg, TINS 12 (1987) 527]. It has been specula ted that such growth may be mediated by cytoskeletal proteins. However, the interaction of GAP-43 with proteins of the presynaptic terminals is poorly characterized. Here, we analyze GAP-43 binding to cytoskeletal proteins by two different biochemical assays, by blot overlay and sedimentation. We fi nd that immobilized brain spectrin (BS) is able to bind GAP-43. In contrast , little binding was observed to microtubule proteins and other elements of the cytoskeleton. Since GAP-43 is located presynaptically, it may bind to the presynaptic form. of BS (SpII Sigma 1). It is attractive to think that such an interaction would participate in the structural plasticity observed in growth cones and adult synapses. (C) 1999 Elsevier Science B.V. All rig hts reserved.