Mutation of Serine 41 in the Neuron-Specific Protein B-50 (GAP-43) Prohibits Phosphorylation by Protein Kinase C

Autor: M. Kasperaitis, H. B. Nielander, Peter Schotman, W.H. Gispen, L.H. Schrama, A.B. Oestreicher, A.J. van Rozen
Rok vydání: 1990
Předmět:
Zdroj: Journal of Neurochemistry. 55:1442-1445
ISSN: 1471-4159
0022-3042
DOI: 10.1111/j.1471-4159.1990.tb03159.x
Popis: The neuron-specific, calmodulin-binding protein B-50 (also known as GAP-43, F1, or neuromodulin) is an endogenous substrate of protein kinase C (PKC). PKC exclusively phosphorylates Ser residues in B-50. As potential phosphorylation sites for PKC, Ser41, Ser110, and Ser122 were indicated, of which Ser41 is contained in the sequence ASF, which matches with the sequence of a synthetic PKC substrate. N-terminally 35S-labeled B-50, produced from cDNA, was subjected to digestion with Staphylococcus aureus V8 protease (SAP). Consecutively, 35S-labeled 28- and 15-kDa fragments were formed, similar to those after digestion of 32P-labeled B-50. In a previous study, we showed that the 32P-labeled 15-kDa SAP fragment contains all 32P radioactivity. The present data indicate that it contains the N-terminus of B-50 as well. The 15-kDa fragment, with a calculated length ranging from amino acid residue 1 to 65, contains only one potential PKC phosphorylation site, at Ser41. Mutagenesis of Ser41 into Thr or Ala resulted in recombinant B-50 products with mobilities on two-dimensional electrophoresis similar to those of the nonmutated recombinant B-50 and the rat brain B-50. Only [Ser41]B-50 was phosphorylated by PKC, whereas [Thr41]- or [Ala41]B-50 did not show any phosphorylation at the positions indicated on the immunoblots. This leads us to the conclusion that Ser41 is the sole phosphorylation site for PKC in vitro.
Databáze: OpenAIRE
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