S-100 protein has been found in the nuclei isolated from the brain cortex of rabbit. The nuclear S-100 constitutes a small portion (0.55 per cent) of the S-100 present in the cytosol. Most of the large and pale nuclei appear to contain much more S-100 than the small and dark ones. The nuclear membrane is permeable in vitro to $100 in presence of divalent cations. Three forms of S-100 occur in subnuclear fractions: free S-100, present in the soluble protein fraction; labile-bound S-100, present in the deoxyribonucleoprotein fraction and stable-bound S-100, present in the residual or 'nucleolar' fraction. The localization of the S-100 in those regions of the nucleus that are most active in RNA synthesis provides basic information for further studies on the possible role of this protein on genomic expression in nervous tissue.

The brain-specific S-100 protein is a neuronal as well as a glial protein. Neuronal 5-100 is a migratory protein from soma to terminal of the hypoglossal, vagus and glossopharyngeal nerves of the rabbit (axonal transport of S-100 protein). There is a distinctive rate of flow for S-100 in the somatic and parasympathetic efferent fibres of such cranial nerves. S-100 PROTEIN (MOORE, 1965)has been shown to be specific to the nervous system and to conserve its immunological identity throughout phylogenesis (LEVINE and MOORE, 1965; MOORE, PEREZ and GEHRING, 1968;KESSLER, LEVINE and FASMAN, 1968). It is generally assumed that S-100 is a glial protein in the CNS (BENDA, 1968; CICERO, COWAN, MOORE and SUNTZEFF, 1970; PEREZ, OLNEY, CICERO, MOORE and BAHN, 1970) but in the peripheral nerves it seems to be primarily an axonal protein (PEREZ and MOORE, 1968). The experiments to be described deal with the neuronal component of the S-100 protein in the cephalic nerves. Evidence will be presented to show that neuronal S-100 is a migratory protein from soma to nerve endings. Other observations on the dynamics of the protein, particularly its trans-synaptic transfer and its selective binding to the nuclear chromatin, will be published elsewhere. The final object of such studies was to gain information about the role of the neuronal S-100 along nervous pathways. Preliminary accounts of this study have appeared (MIANI, 1971). M E T H O D SLabelling of the somatic and autonomic efferent nuclei of the hypoglossal, vagus andglossopharyngeal nerves. Adult rabbits of 2.5-3.0 kg were employed throughout this investigation. The nuclei and the surrounding structures of the medulla were labelled with 100 pCi of a 1 : 1 mixture of ~L-[4,5~H]lysine and ~-[4,5~H]leucine (New England Nuclear), as described elsewere (MIANI, 1963).Structures under study andpreparative procedures. Three sets of experiments were performed : (1) At different time intervals after labelling the medulla, the cervical vagus from just below the nodose ganglion and the hypoglossal nerve were rapidly collected from both sides of eight animals (728 & S.D. 79 mg, fresh weight), minced and homogenized in a rough glass-glass Potter-Elvehjem homogenizer in 10 vol. of 5 mM-tris-phosphate buffer (pH 7.3). All operations were carried out at 04°C. The homogenate was centrifuged for 1 h at 105,000 g in the Spinco 40 rotor and the supernatant fluid was transferred to a Sephadex G-25 column (2 x 85 cm) in equilibrium with 5 mM-triS buffer. The soluble proteins excluded from Sephadex G-25 column were fractionated on a DEAE-Sephadex A-50 column (1 x 25 cm) according to the procedure of MOORE and MCGREGOR (1965). Fractions of 5 ml were collected, and protein, radioactivity and the S-100 protein were determined. When required, the contents of the tubes from the chromatography containing the S-100 protein were pooled, concentrated to 1 ml by pressure dialysis in 5 mM-tris buffer and then freeze-dried. The residue was dissolved in 50 pl of distilled water and samples (20 pl) subjected to ele...

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Abstract— A procedure has been developed which allows the isolation from rat brain cytosol of a soluble acidic protein, designated DNA‐110 protein, having two basic properties: selective affinity for single‐stranded DNA and immunological specificity to the nervous system. Only two major purification steps, DNA‐cellulose chromatography and affinity chromatography on immunoadsorbents are needed to give apparently pure protein. The purification steps of the DNA‐110 protein have been followed by immunological assay. DNA‐110 has a molecular weight of 68,000 and an isoelectric point of 5.9. It accounts for 1.95% of the total soluble protein and its concentration is 216 μg per g wet weight of rat brain. DNA‐110 is immunologically unrelated to other soluble acidic brain‐specific proteins and glycoproteins.

Abstract— The myelin fraction isolated by isopycnic gradient centrifugation from rabbit nerve is able to synthesize ATP at substrate level through the Embden‐Meyerhof pathway. Suitable conditions are described to preserve the association of glycolytic enzymes with isolated myelin. Except for phosphofructokinase and ketose‐1‐phosphate aldolase, all the remaining glycolytic enzymes are present in the myelin. A wide divergence was found in the firmness of the association of individual glycolytic enzymes with myelin under the condition of isolation; some, like glucosephosphate isomerase and glyceraldehydephosphate dehydrogenase were retained in high percentage (about 60 per cent of the activity of the homogenate is myelin‐bound); others were weakly bound (no more than 7–6 percent of the lactate dehydrogenase activity of the homogenate is myelin‐bound). By using glyceraldehyde‐3‐phosphate as substrate for glycolysis, about 25 per cent of the total glycolytic activity of rabbit‐nerve homogenate is associated with the myelin. Glucosephosphate isomerase and lactate dehydrogenase may be extracted from and readily recombined with the myelin.