Skip to main content
PMC home page
The Journal of Cell Biology logoLink to The Journal of Cell Biology
. 1989 May 1;108(5):1863–1872. doi: 10.1083/jcb.108.5.1863

Interactions of synapsin I with small synaptic vesicles: distinct sites in synapsin I bind to vesicle phospholipids and vesicle proteins

PMCID: PMC2115532  PMID: 2497106

Abstract

Synapsin I is a major neuron-specific phosphoprotein that is specifically localized to the cytoplasmic surface of small synaptic vesicles. In the present study, the binding of synapsin I to small synaptic vesicles was characterized in detail. The binding of synapsin I was preserved when synaptic vesicles were solubilized and reconstituted in phosphatidylcholine. After separation of the protein and lipid components of synaptic vesicles under nondenaturing conditions, synapsin I bound to both components. The use of hydrophobic labeling procedures allowed the assessment of interactions between phospholipids and synapsin I in intact synaptic vesicles. Hydrophobic photolabeling followed by cysteine-specific cleavage of synapsin I demonstrated that the head domain of synapsin I penetrates into the hydrophobic core of the bilayer. The purified NH2-terminal fragment, derived from the head domain by cysteine-specific cleavage, bound to synaptic vesicles with high affinity confirming the results obtained from hydrophobic photolabeling. Synapsin I binding to synaptic vesicles could be inhibited by the entire molecule or by the combined presence of the NH2-terminal and tail fragments, but not by an excess of either NH2-terminal or tail fragment alone. The purified tail fragment bound with relatively high affinity to synaptic vesicles, though it did not significantly interact with phospholipids. Binding of the tail fragment was competed by holosynapsin I; was greatly decreased by phosphorylation; and was abolished by high ionic strength conditions or protease treatment of synaptic vesicles. The data suggest the existence of two sites of interaction between synapsin I and small synaptic vesicles: binding of the head domain to vesicle phospholipids and of the tail domain to a protein component of the vesicle membrane. The latter interaction is apparently responsible for the salt and phosphorylation dependency of synapsin I binding to small synaptic vesicles.

Full Text

The Full Text of this article is available as a PDF (1.5 MB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Batteiger B., Newhall W. J., 5th, Jones R. B. The use of Tween 20 as a blocking agent in the immunological detection of proteins transferred to nitrocellulose membranes. J Immunol Methods. 1982 Dec 30;55(3):297–307. doi: 10.1016/0022-1759(82)90089-8. [DOI] [PubMed] [Google Scholar]
  2. Benfenati F., Greengard P., Brunner J., Bähler M. Electrostatic and hydrophobic interactions of synapsin I and synapsin I fragments with phospholipid bilayers. J Cell Biol. 1989 May;108(5):1851–1862. doi: 10.1083/jcb.108.5.1851. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1006/abio.1976.9999. [DOI] [PubMed] [Google Scholar]
  4. Browning M. D., Huang C. K., Greengard P. Similarities between protein IIIa and protein IIIb, two prominent synaptic vesicle-associated phosphoproteins. J Neurosci. 1987 Mar;7(3):847–853. doi: 10.1523/JNEUROSCI.07-03-00847.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bähler M., Benfenati F., Valtorta F., Czernik A. J., Greengard P. Characterization of synapsin I fragments produced by cysteine-specific cleavage: a study of their interactions with F-actin. J Cell Biol. 1989 May;108(5):1841–1849. doi: 10.1083/jcb.108.5.1841. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Bähler M., Greengard P. Synapsin I bundles F-actin in a phosphorylation-dependent manner. Nature. 1987 Apr 16;326(6114):704–707. doi: 10.1038/326704a0. [DOI] [PubMed] [Google Scholar]
  7. Czernik A. J., Pang D. T., Greengard P. Amino acid sequences surrounding the cAMP-dependent and calcium/calmodulin-dependent phosphorylation sites in rat and bovine synapsin I. Proc Natl Acad Sci U S A. 1987 Nov;84(21):7518–7522. doi: 10.1073/pnas.84.21.7518. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. De Camilli P., Cameron R., Greengard P. Synapsin I (protein I), a nerve terminal-specific phosphoprotein. I. Its general distribution in synapses of the central and peripheral nervous system demonstrated by immunofluorescence in frozen and plastic sections. J Cell Biol. 1983 May;96(5):1337–1354. doi: 10.1083/jcb.96.5.1337. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. De Camilli P., Greengard P. Synapsin I: a synaptic vesicle-associated neuronal phosphoprotein. Biochem Pharmacol. 1986 Dec 15;35(24):4349–4357. doi: 10.1016/0006-2952(86)90747-1. [DOI] [PubMed] [Google Scholar]
  10. De Camilli P., Harris S. M., Jr, Huttner W. B., Greengard P. Synapsin I (Protein I), a nerve terminal-specific phosphoprotein. II. Its specific association with synaptic vesicles demonstrated by immunocytochemistry in agarose-embedded synaptosomes. J Cell Biol. 1983 May;96(5):1355–1373. doi: 10.1083/jcb.96.5.1355. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Goelz S. E., Nestler E. J., Chehrazi B., Greengard P. Distribution of protein I in mammalian brain as determined by a detergent-based radioimmunoassay. Proc Natl Acad Sci U S A. 1981 Apr;78(4):2130–2134. doi: 10.1073/pnas.78.4.2130. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Harter C., Bächi T., Semenza G., Brunner J. Hydrophobic photolabeling identifies BHA2 as the subunit mediating the interaction of bromelain-solubilized influenza virus hemagglutinin with liposomes at low pH. Biochemistry. 1988 Mar 22;27(6):1856–1864. doi: 10.1021/bi00406a010. [DOI] [PubMed] [Google Scholar]
  13. Helenius A., Simons K. Solubilization of membranes by detergents. Biochim Biophys Acta. 1975 Mar 25;415(1):29–79. doi: 10.1016/0304-4157(75)90016-7. [DOI] [PubMed] [Google Scholar]
  14. Helenius A., Simons K. The binding of detergents to lipophilic and hydrophilic proteins. J Biol Chem. 1972 Jun 10;247(11):3656–3661. [PubMed] [Google Scholar]
  15. Huang C. K., Browning M. D., Greengard P. Purification and characterization of protein IIIb, a mammalian brain phosphoprotein. J Biol Chem. 1982 Jun 10;257(11):6524–6528. [PubMed] [Google Scholar]
  16. Huttner W. B., DeGennaro L. J., Greengard P. Differential phosphorylation of multiple sites in purified protein I by cyclic AMP-dependent and calcium-dependent protein kinases. J Biol Chem. 1981 Feb 10;256(3):1482–1488. [PubMed] [Google Scholar]
  17. Huttner W. B., Schiebler W., Greengard P., De Camilli P. Synapsin I (protein I), a nerve terminal-specific phosphoprotein. III. Its association with synaptic vesicles studied in a highly purified synaptic vesicle preparation. J Cell Biol. 1983 May;96(5):1374–1388. doi: 10.1083/jcb.96.5.1374. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Jahn R., Schiebler W., Greengard P. A quantitative dot-immunobinding assay for proteins using nitrocellulose membrane filters. Proc Natl Acad Sci U S A. 1984 Mar;81(6):1684–1687. doi: 10.1073/pnas.81.6.1684. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Jahn R., Schiebler W., Ouimet C., Greengard P. A 38,000-dalton membrane protein (p38) present in synaptic vesicles. Proc Natl Acad Sci U S A. 1985 Jun;82(12):4137–4141. doi: 10.1073/pnas.82.12.4137. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  21. Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
  22. Leto T. L., Marchesi V. T. A structural model of human erythrocyte protein 4.1. J Biol Chem. 1984 Apr 10;259(7):4603–4608. [PubMed] [Google Scholar]
  23. Llinás R., McGuinness T. L., Leonard C. S., Sugimori M., Greengard P. Intraterminal injection of synapsin I or calcium/calmodulin-dependent protein kinase II alters neurotransmitter release at the squid giant synapse. Proc Natl Acad Sci U S A. 1985 May;82(9):3035–3039. doi: 10.1073/pnas.82.9.3035. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Matsudaira P., Jakes R., Cameron L., Atherton E. Mapping the cysteine residues and actin-binding regions of villin by using antisera to the amino and carboxyl termini of the molecule. Proc Natl Acad Sci U S A. 1985 Oct;82(20):6788–6792. doi: 10.1073/pnas.82.20.6788. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Matthew W. D., Tsavaler L., Reichardt L. F. Identification of a synaptic vesicle-specific membrane protein with a wide distribution in neuronal and neurosecretory tissue. J Cell Biol. 1981 Oct;91(1):257–269. doi: 10.1083/jcb.91.1.257. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. McGuinness T. L., Lai Y., Greengard P. Ca2+/calmodulin-dependent protein kinase II. Isozymic forms from rat forebrain and cerebellum. J Biol Chem. 1985 Feb 10;260(3):1696–1704. [PubMed] [Google Scholar]
  27. Nairn A. C., Hemmings H. C., Jr, Greengard P. Protein kinases in the brain. Annu Rev Biochem. 1985;54:931–976. doi: 10.1146/annurev.bi.54.070185.004435. [DOI] [PubMed] [Google Scholar]
  28. Navone F., Greengard P., De Camilli P. Synapsin I in nerve terminals: selective association with small synaptic vesicles. Science. 1984 Dec 7;226(4679):1209–1211. doi: 10.1126/science.6438799. [DOI] [PubMed] [Google Scholar]
  29. Schiebler W., Jahn R., Doucet J. P., Rothlein J., Greengard P. Characterization of synapsin I binding to small synaptic vesicles. J Biol Chem. 1986 Jun 25;261(18):8383–8390. [PubMed] [Google Scholar]
  30. Sieghart W., Forn J., Schwarcz R., Coyle J. T., Greengard P. Neuronal localization of specific brain phosphoproteins. Brain Res. 1978 Nov 10;156(2):345–350. doi: 10.1016/0006-8993(78)90516-4. [DOI] [PubMed] [Google Scholar]
  31. Südhof T. C., Lottspeich F., Greengard P., Mehl E., Jahn R. A synaptic vesicle protein with a novel cytoplasmic domain and four transmembrane regions. Science. 1987 Nov 20;238(4830):1142–1144. doi: 10.1126/science.3120313. [DOI] [PubMed] [Google Scholar]
  32. Towbin H., Staehelin T., Gordon J. Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350–4354. doi: 10.1073/pnas.76.9.4350. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Ueda T. Attachment of the synapse-specific phosphoprotein protein I to the synaptic membrane: a possible role of the collagenase-sensitive region of protein I. J Neurochem. 1981 Jan;36(1):297–300. doi: 10.1111/j.1471-4159.1981.tb02408.x. [DOI] [PubMed] [Google Scholar]
  34. Ueda T., Greengard P. Adenosine 3':5'-monophosphate-regulated phosphoprotein system of neuronal membranes. I. Solubilization, purification, and some properties of an endogenous phosphoprotein. J Biol Chem. 1977 Jul 25;252(14):5155–5163. [PubMed] [Google Scholar]
  35. Watterson D. M., Harrelson W. G., Jr, Keller P. M., Sharief F., Vanaman T. C. Structural similarities between the Ca2+-dependent regulatory proteins of 3':5'-cyclic nucleotide phosphodiesterase and actomyosin ATPase. J Biol Chem. 1976 Aug 10;251(15):4501–4513. [PubMed] [Google Scholar]
  36. Wiedenmann B., Franke W. W. Identification and localization of synaptophysin, an integral membrane glycoprotein of Mr 38,000 characteristic of presynaptic vesicles. Cell. 1985 Jul;41(3):1017–1028. doi: 10.1016/s0092-8674(85)80082-9. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Cell Biology are provided here courtesy of The Rockefeller University Press

RESOURCES