CIQUIBIC   05472
CENTRO DE INVESTIGACIONES EN QUIMICA BIOLOGICA DE CORDOBA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Acylation of GAP-43 is regulated by electrostatic interactions between its polybasic domain and PI4P.
Autor/es:
TRENCHI, ALEJANDRA; GOMEZ, GUILLERMO; DANIOTTI, JOSE LUIS
Lugar:
Carlos Paz, Cordoba
Reunión:
Congreso; 44 Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2008
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)
Resumen:
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The growth-associated
protein-43 (GAP-43) is a dually acylated protein at cysteines 3 and 4 and
contains a polybasic domain (aa 32-55) which is able to bind anionic lipids. The
aim of this study was to investigate if the polybasic domain modulates the
acylation state of GAP-43. Using biochemical assays and live cell fluorescence
microscopy, it was demonstrated that after synthesized in the cytosol, GAP-43
is acylated at the trans-Golgi network (TGN), which is necessary for its stable
association with membranes. By comparing N-terminal region (aa 1-13, N13GAP-43)
and full-length GAP-43 (GAP-43full), it was found that basic
residues of GAP-43 could be modulating both its adsorption to TGN and palmitoyl-acyl
transferase accessibility. We speculated that the polybasic domain from GAP-43 could
be electrostatically interacting with PIP4, an anionic phospholipid highly
concentrated at the TGN through an ADP-ribosylation factor 1 (Arf1)-mediated
process. In this sense, we observed that Arf1 inhibition did not affect acylation
and TGN and plasma membrane association of N13GAP-43 but severely
affected subcellular distribution of GAP-43full and its adsorption
to TGN, thereby increasing the cytosolic pool of this protein. We conclude that
Arf1 activity, through its effector PI4P, is required for TGN adsorption of GAP-43full
via its polybasic domain.