IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Interactions between GAP-43 and model membranes through electrostatic and hydrophobic interactions
Autor/es:
RODI, P.; GONZALEZ POLO, V.; PATTERSON, S.I.; GENNARO, A.M.
Lugar:
Buzios, Brasil
Reunión:
Congreso; VII Congreso Iberoamericano de Biofísica; 2009
Resumen:
The growth-associated protein-43 (GAP-43) is very abundant in developing and regenerating neurons and is also found in some neurons in the adult brain. GAP-43 is mainly localized at the plasma membrane and contributes to the mechanism of axonal outgrowth in embryo and to axonal regeneration in the adult. This protein has a fundamental role in neuronal regeneration processes. GAP-43 has two important basic regions in the N-terminal.  The first region (aa 1-13), according to some authors, is responsible of the first event of binding to membranes due to the S-acylation of cysteines 3 and 4. The other region contains the basic effector domain organized in an alpha-helical secondary structure when it interacts with membranes. This domain binds anionic lipids in both model and cellular systems, operates as a calmodulin (CaM)-binding region (aa 39-55) and contains a protein kinase C (PKC) phosphorylation site at serine 41. It has been proposed that GAP-43 accumulates at detergent-insoluble, cholesterol-dependent rafts at the inner leaflet of the plasma membrane that are enriched in acidic phospholipids. GAP-43 becomes bound via palmitoylation but the palmitate chains do not serve as permanent membrane anchors, because at steady-state most of the GAP-43 in a cell is membrane-bound but is not palmitoylated. It has been shown that when Arg-6, Arg-7, Lys-9, and Lys-13 were replaced by uncharged residues, GAP-43 was not retained at the membrane upon depalmitoylation. In the present work we investigate GAP-43-membrane interactions.  GAP-43 was produced and purified from bacteria, and palmitoylation was performed in vitro with palmitoyl-CoA.  The interaction of both forms of the protein with different kinds of liposomes was studied.