Phosphorylation of septin 3 on Ser-91 by cGMP-dependent protein kinase-1 in nerve terminals
Date
2004
Authors
Xue, Jing
Milburn, Peter J
Hanna, Bernadette
Graham, Mark E
Rostas, John A P
Robinson, Phillip J
Journal Title
Journal ISSN
Volume Title
Publisher
Portland Press
Abstract
The septins are a family of GTPase enzymes required for cytokinesis and play a role in exocytosis. Among the ten vertebrate septins, Sept5 (CDCrel-1) and Sept3 (G-septin) are primarily concentrated in the brain, wherein Sept3 is a substrate for PKG-I (cGMP-dependent protein kinase-I) in nerve terminals. There are two motifs for potential PKG-I phosphorylation in Sept3, Thr-55 and Ser-91, but phosphoamino acid analysis revealed that the primary site is a serine. Derivatization of phosphoserine to S-propylcysteine followed by N-terminal sequence analysis revealed Ser-91 as a major phosphorylation site. Tandem MS revealed a single phosphorylation site at Ser-91. Substitution of Ser-91 with Ala in a synthetic peptide abolished phosphorylation. Mutation of Ser-91 to Ala in recombinant Sept3 also abolished PKG phosphorylation, confirming that Ser-91 is the major site in vitro. Antibodies raised against a peptide containing phospho-Ser-91 detected phospho-Sept3 only in the cytosol of nerve terminals, whereas Sept3 was located in a peripheral membrane extract. Therefore Sept3 is phosphorylated on Ser-91 in nerve terminals and its phosphorylation may contribute to the regulation of its subcellular localization in neurons.
Description
Keywords
Keywords: Polypeptides; Proteins; Substitution reactions; Substrates; Phosphorylation; Vertebrate septins; Biochemistry; brain enzyme; cyclic GMP dependent protein kinase; cyclic GMP dependent protein kinase I; cysteine derivative; guanosine triphosphatase; phospho cGMP; cGMP-dependent protein kinase (PKG); Protein phosphorylation; Sept3; Septins; Synaptosomes
Citation
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Source
Biochemical Journal
Type
Journal article