Phosphorylation-dependent effects of synapsin IIa on actin polymerization and network formation

Hendrikus B. Nielander, Franco Onofri, Eric Schaeffer, Andrea Menegon, Riccardo Fesce, Flavia Valtorta, Paul Greengard, Fabio Benfenati

Research output: Contribution to journalArticle


The synapsins are a family of synaptic vesicle phosphoproteins which play a key role in the regulation of neurotransmitter release and synapse formation. In the case of synapsin I, these biological properties have been attributed to its ability to interact with both synaptic vesicles and the actin-based cytoskeleton. Although synapsin II shares some of the biological properties of synapsin I, much less is known of its molecular properties. We have investigated the interactions of recombinant rat synapsin IIa with monomeric and filamentous actin and the sensitivity of those interactions to phosphorylation, and found that: i) dephosphorylated synapsin II stimulates actin polymerization by binding to actin monomers and forming actively elongating nuclei and by facilitating the spontaneous nucleation/elongation processes; ii) dephosphorylated synapsin II induces the formation of thick and ordered bundles of actin filaments with greater potency than synapsin I; iii) phosphorylation by protein kinase A markedly inhibits the ability of synapsin II to interact with both actin monomers and filaments. The results indicate that the interactions of synapsin II with actin are similar but not identical to those of synapsin] and suggest that synapsin II may play a major structural role in mature and developing nerve terminals, which is only partially overlapping with the role played by synapsin I.

Original languageEnglish
Pages (from-to)2712-2722
Number of pages11
JournalEuropean Journal of Neuroscience
Issue number12
Publication statusPublished - 1997



  • Cytoskeleton
  • Exocytosis
  • Rat
  • Synaptic vesicles
  • Synaptogenesis

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Nielander, H. B., Onofri, F., Schaeffer, E., Menegon, A., Fesce, R., Valtorta, F., Greengard, P., & Benfenati, F. (1997). Phosphorylation-dependent effects of synapsin IIa on actin polymerization and network formation. European Journal of Neuroscience, 9(12), 2712-2722.