Isolation and Structural Studies on Synaptic Complexes From Rat Brain

Cotman, Carl W.; Taylor, Dwan A.

doi:10.1083/jcb.55.3.696

Cited by 266 publications

(145 citation statements)

References 22 publications

(28 reference statements)

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“…Con A sites closely correspond in location to the postsynaptic membrane projections (bristles) which are also localized on the surface of the postsynaptic membrane overlying the PSD (Van der Loos, 1963;Cotman and Taylor, 1972). By comparison, in agreement with data reported by Matus et al (1973) both the inner surface of the synaptic membrane and the PSD bind very little Con A conjugate.…”

Section: A-d)supporting

confidence: 77%

“…1 a). The ferritin molecules were seen lined up along the cleft in close correspondence to the surface specializations ("bristles") of the postsynaptic membrane previously reported (Cotman and Taylor, 1972). a-MG inhibited the labeling of the cleft area (Fig.…”

Section: Resultsmentioning

confidence: 88%

“…Hence the Con A receptors in the cleft appear to be immobile. It may be, as suggested previously (Cotman and Taylor, 1972), that the specialized postsynaptic binding sites are stabilized by the PSD, which serves to restrict the diffusion of these and perhaps other synaptic molecules away from the synaptic area. This possibility derives some support from studies on other membranes where the lateral diffusion of proteins on the surface is restricted by proteins located on the cytoplasmic side of the membrane (Nicolson, 1973;Nicolson and Painter, 1973).…”

Section: A-d)mentioning

confidence: 87%

“…Subcellular fractions were prepared from the forebrain of adult rats by standard procedures. Synaptosomal and synaptic plasma membrane fractions were prepared as described by Cotman and Matthews (1971) and SJC, previously referred to as synaptic complexes, were prepared by the method of Cotman and Taylor (1972). in the isolation of SJC, a synaptic membrane (SM) fraction was treated with 0.5% Triton X-100 before density gradient centrifugation.…”

Section: Methodsmentioning

confidence: 99%

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Localization and Characterization of Concanavalin a Receptors in the Synaptic Cleft

Cotman

Taylor

1974

The Journal of Cell Biology

110

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Section: A-d)supporting

confidence: 77%

Section: Resultsmentioning

confidence: 88%

Section: A-d)mentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Localization and Characterization of Concanavalin a Receptors in the Synaptic Cleft

Cotman

Taylor

1974

The Journal of Cell Biology

110

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“…This synapse-cytoskeletal network probably aids in providing structural and functional communication between synapses within a neuron. The PSD appears held together by disulfide bonds (21), hydrophobic interactions, and calcium coordination bonds (22,23), so that factors affecting these bonds would affect the static and dynamic properties of the PSD and its interaction with the neuron's cytoskeletal network. We would anticipate that synaptic activity may influence these interactions.…”

Section: Discussionmentioning

confidence: 99%

Identification of a protein related to tubulin in the postsynaptic density.

Feit¹,

Kelly²,

Cotman³

1977

Proc. Natl. Acad. Sci. U.S.A.

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The postsynaptic density is a unique subcellular organelle associated with the synaptic complex and appears as an electron-dense area immediately subjacent to the postsynaptic plasma membrane. The postsynaptic density was isolated from the synaptosomal fraction and the protein constituents were analyzed by polyacrylamide gel electrophoresis. Polypeptides closely related to tubulin were identified as a major component of the postsynaptic density on the basis of molecular weight, subunit structure, and peptide map criteria.Knowledge of the molecular constituents of the synapse is essential in order to understand the underlying mechanisms in the development, maintenance, and plasticity of synaptic connections. At the synapse in the central nervous system, preand postsynaptic membranes are specialized where they are joined. The presynaptic membrane often displays a set of electron-dense projections on its cytoplasmic surface, while on its inner surface the postsynaptic plasma membrane is often distinguished by the presence of an electron-dense structure called the postsynaptic density (PSD). The PSD is not found in all classes of synapses, but in the central nervous system, a prominent PSD is associated with excitatory axodendritic synapses. Neither the functional role nor the exact composition of the PSD is known at present.Identification of the various components of the synapse is dependent on suitable subcellular fractionation techniques. In recent years techniques have been devised for the isolation of synaptic vesicles, synaptic plasma membranes, and most recently, the PSD (1). The PSD fraction can be isolated by treatment of the synaptic plasma membrane fraction with sodium N-lauroyl sarcosinate, followed by density gradient centrifugation. The product of this procedure is a highly purified fraction of PSDs. In the electron microscope isolated PSDs are devoid of their adherent plasma membrane and appear as fibrous and granular matrix which closely resembles that seen in micrographs of intact tissue. Isolated PSDs also retain their distinctive cytochemical properties (1).Isolated PSDs consist primarily of protein with a small amount of carbohydrate and lipid (2). After sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gel electrophoresis, a single band contains about 40% of the total protein, and therefore this polypeptide(s) probably constitutes the molecular backbone or skeleton of the structure seen in the electron microscope. The apparent molecular weight of this major protein band is 52,000-54,000. On the basis of its molecular weight, which is similar to tubulin, it was suggested that the polypeptide might be tubulin or a very similar protein (2). Tubulin (or a closely related protein) has been identified as a major constituent of both the soluble and insoluble components of the synaptosome (3-5), even though intact microtubules are usually not found at the synapse.In this study we have examined the possibility that tubulin is a major component of the PSD with regard to two criteria: (i) resolution...

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Immunoelectron‐microscopic localization of the 180 kD component of the neural cell adhesion molecule N‐CAM in postsynaptic membranes

Persohn¹,

Pollerberg²,

Schachner³

1989

J of Comparative Neurology

184

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In order to investigate the expression of cell adhesion molecules in synapses, we have studied the localization of the neural cell adhesion molecule N-CAM in the cerebellum and hippocampus of adult mice by immunocytological and immunochemical methods. Of the three molecular components of N-CAM with relative molecular masses (Mr) of 120, 140, and 180 kD, N-CAM 120 is not detectable in synaptosomal membranes, whereas N-CAM 140 is expressed on both pre- and postsynaptic membranes and N-CAM 180 is restricted to postsynaptic sites, with localization of the N-CAM 180-specific epitope in postsynaptic densities. Specificity of immunoreactivity is indicated by the observation that antibodies to the neural cell adhesion molecule L1 do not label synaptic membranes, whereas antibodies to two major components of postsynaptic densities, actin and erythrocyte spectrin, react with synaptic structures. Interestingly, N-CAM 180 is only detectable in subpopulations of synapses in the intact tissue. Isolated synaptosomes, opened for unimpeded accessibility of antibody by hypoosmotic treatment, also reveal a partial expression of N-CAM 180 in that 67% are labeled by antibodies to N-CAM 180, while antibodies to actin and erythrocyte spectrin react with 95% and 88% of all synaptosomes, respectively. N-CAM 180 does not appear to be differentially expressed in synapses of a particular morphological type, but is detectable in all types of synapses in the cerebellum and hippocampus, except for mossy fiber synapses and synapses between basket and Purkinje cells, which are generally N-CAM 180-negative. Since N-CAM 180 has been shown to be characteristic of stabilized or stabilizing cell contacts, possibly by its association with the cytoskeleton-membrane linker protein spectrin (Pollerberg et al.: J. Cell Biol. 101:1921-1929, '85; Nature 324:462-465, '86; Cell Tissue Res. 250:227-236, '87), we would like to suggest N-CAM 180 plays an important role in determining the stability of contacts between pre- and postsynaptic membranes and state of synaptic activity.

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Isolation and Structural Studies on Synaptic Complexes From Rat Brain

Cited by 266 publications

References 22 publications

Localization and Characterization of Concanavalin a Receptors in the Synaptic Cleft

Localization and Characterization of Concanavalin a Receptors in the Synaptic Cleft

Identification of a protein related to tubulin in the postsynaptic density.

Immunoelectron‐microscopic localization of the 180 kD component of the neural cell adhesion molecule N‐CAM in postsynaptic membranes

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