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Effects of Gangliosides GM1 and GD1 a on GAP‐43 Phosphorylation and Dephosphorylation in Isolated Growth Cones
Author(s) -
Meiri Karina F.,
Beverly Marcia
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.62010291.x
Subject(s) - dephosphorylation , phosphorylation , chemistry , microbiology and biotechnology , growth cone , biochemistry , biophysics , biology , phosphatase , axon
Phosphorylation of the nervous system‐specific protein GAP‐43 in growth cones in vivo increases as the growth cones near their targets, at a time when the gangliosides GM1 and GD1a are being accumulated in the growth cone membrane, thus raising the possibility that the gangliosides could modulate GAP‐43 behavior. We used a subcellular fraction of intact isolated growth cones to show that both GM1 and GD1a affected the calcium‐ dependent posttranslational regulation of GAP‐43 in several similar ways. Both gangliosides induced rapid incorporation of phosphate into GAP‐43; however, the induction was undetectable with our antibody 2G12 that is specific for kinase C‐phosphorylated GAP‐43. Furthermore, neither ganglioside stimulated kinase C activity in isolated growth cones, suggesting that the rapid Phosphorylation may not be on Ser 41 , the kinase C site. However, both gangliosides did induce a slower accumulation of GAP‐43 phosphorylated on Ser 41 , apparently by inhibiting a phosphatase. Finally, calcium‐dependent proteolysis of GAP‐43 was also stimulated by both GM1 and GD1a. In contrast, GD1a, but not GM1, caused the redistribution of GAP‐43 into the isolated growth cone cytoskeleton. The results demonstrate that both gangliosides can modulate the calcium‐dependent regulation of GAP‐43.