Not growth associated protein GAP-43 (B-50), but its fragment GAP-43-3 (B-60) predominates in rat brain during development

The participation of the nerve termini growth associated protein GAP-43 in neurite outgrowth and targeting is well documented. Commonly, besides GAP-4 3 itself, two big fragments devoid of four (GAP-43-2, IB-50) and of about 4 0 (GAP-43-3, B-60) N-terminal residues were co-isolated from brain. In adul t brain, GAP-43 significantly prevails over the fragments. To find their re lative amounts during development, rat brain proteins were isolated on diff erent stages of embryonal and post-natal development and subjected to gel e lectrophoresis in 0.9 M acetic acid-2.5 M urea system. The bands of GAP-43 protein family were detected on Western blots. We show that in developing b rain (until 5th post-natal day), a proteolysis of GAP-43 near Ser(41) that results in GAP-43-3 accumulation is activated. We hypothesize that just the functions that can be performed by the GAP-43 fragments are of importance for developing brain. (C) 2001 Elsevier Science Ireland Ltd. All rights res erved.