The domain of brain β-spectrin responsible for synaptic vesicle association is essential for synaptic transmission

• Published in: Brain research Vol. 881; no. 1; pp. 18 - 27
• Main Authors: Zimmer, Warren E., Zhao, Ying, Sikorski, Aleksander F., Critz, Stuart D., Sangerman, José, Elferink, Lisa A., Xu, X.Susan, Goodman, Steven R.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 20-10-2000; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Antibodies - pharmacology; b-Spectrin; Biological and medical sciences; Carrier Proteins - metabolism; Cattle; Cell physiology; Fundamental and applied biological sciences. Psychology; Molecular and cellular biology; Neurotransmission; Protein Isoforms - metabolism; Spectrin; Spectrin - metabolism; Synapsin; Synapsins - metabolism; Synaptic transmission; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Synaptic vesicle; Synaptic Vesicles - drug effects; Synaptic Vesicles - metabolism; Spectrin; Synaptic vesicle; Excitable membranes and synaptic transmission; Synapsin; Synaptic transmission; Central nervous system; Binding site; Molecular domain; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(00)02796-7

We have examined the interaction between synapsin I, the major phosphoprotein on the membrane of small synaptic vesicles, and brain spectrin. Using recombinant peptides we have localized the synapsin I attachment site upon the β-spectrin isoform βSpIIΣI to a region of 25 amino acids, residues 211 through 235. This segment is adjacent to the actin binding domain and is within the region of the βSpIIΣI that we previously predicted as a candidate synapsin I binding domain based upon sequence homology. We used differential centrifugation techniques to quantitatively assess the interaction of spectrin with synaptic vesicles. Using this assay, high affinity saturable binding of recombinant βSpIIΣI proteins was observed with synaptic vesicles. Binding was only observed when the 25 amino acid synapsin I binding site was included on the recombinant peptides. Further, we demonstrate that antibodies directed against 15 amino acids of the synapsin I binding domain specifically blocked synaptic transmission in cultured hippocampal neurons. Thus, the synapsin I attachment site on βSpIIΣI spectrin comprises a ∼25 amino acid segment of the molecule and interaction of these two proteins is an essential step for the process of neurotransmission.