Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Morphological evidence is presented indicating sites of synthesis, storage, and release of neurotransmitters in dendrites of dopaminergic cells of the substantia nigra and cholinergic cells of the neostriatum. Smooth endoplasmic reticulum can be identified in dopaminergic neurons touching the dendritic surface. The false transmitter for dopamine, 5-hydroxydopamine (5-OHDA), is localized to smooth endoplasmic reticulum or large vesicular structures which approach the dendritic surface. The dopamine synthesizing enzyme, tyrosine hydroxylase (TH), is localized to microtubules and smooth endoplasmic reticulum which approach the postsynaptic membrane. In the neostriatum, dopaminergic nerve endings make asymmetrical axospinous contacts. The postsynaptic spines often contain a few 'vesicles' near the postsynaptic thickenings. The surface and subsurface structures stain preferentially for choline acetyltransferase (CAT), the synthesizing enzyme for acetylcholine. It is hypothesized that neurotransmitters are released from dendrites as a general phenomenon in the CNS and that they can act upon axonal endings.
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PMID:Dendro axonic neurotransmission. II. Morphological sites for the synthesis, binding and release of neurotransmitters in dopaminergic dendrites in the substantia nigra and cholinergic dendrites in the neostriatum. 3 84

The components of biological membranes are asymmetrically distributed between the membrane surfaces. Proteins are absolutely asymmetrical in that every copy of a polypeptide chain has the same orientation in the membrane, and lipids are nonabsolutely asymmetrical in that almost every type of lipid is present on both sides of the bilayer, but in different and highly variable amounts. Asymmetry is maintained by lack of transmembrane diffusion. Two types of membrane proteins, called ectoproteins and endoproteins, are distinguished. Biosynthetic pathways for both types of proteins and for membrane lipids are inferred from their topography and distribution in the formed cells. Note added in proof. A cell-free system has now been developed which permits the mechanisms of membrane protein assembly to be studied (108). The membrane glycoprotein of vesicular stomatitis virus has been synthesized by wheat germ ribosomes in the presence of rough endoplasmic reticulum from pancreas. The resulting polypeptide is incorporated into the membrane, spans the lipid bilayer asymmetrically, and is glycosylated (108). The amino terminal portion of this transmembrane protein is found inside the endoplasmic reticulum vesicle, while the carboxyl terminal portion is exposed on the outer surface of the vesicle. Furthermore, addition of the glycoprotein to membranes after protein synthesis does not result in incorporation of the protein into the membrane in the manner described above (108). Consequently, protein synthesis and incorporation into the membrane must be closely coupled. Indeed, using techniques to synchronize the growth of nascent polypeptides, it has been shown (109) that no more than one-fourth of the glycoprotein chain can be made in the absence of membranes and still cross the lipid bilayer when chains are subsequently completed in the presence of membranes. These findings demonstrate directly that the extracytoplasmic portion of an ectoprotein can cross the membrane only during biosynthesis, and not after.
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PMID:Membrane asymmetry. 40 30

Two types of neurons, projection and intrinsic, previously identified in Golgi preparations of the adult monkey (Macaca mulatta) basilar pontine gray (Cooper and Fox, '76) were observed electronmicroscopically in Macaca mulatta and the squirrel monkey Saimiri sciureus. The cell body of the projection neuron measures up to 37 micrometer and its cytoplasm is rich in organelles. The Goli apparatus, ribosomes, and mitochondria are disposed around the nucleus, while rough endoplasmic reticulum though abundant is usually confined to one half of the cell body. The cell body of the intrinsic neuron measures less than 20 micrometer and its cytoplasm displays prominent ribosomes, but a paucity of other organelles. Five types of synaptic profiles have been identified in the neuropil of the basilar pons; one measures up to 5 micrometer and the rest 2 micrometer or less. They are: (1) a large profile (MSV) containing medium size vesicles (500A) and a central core of mitochondria and neurofilaments; (2) a profile (SSV) containing small round vesicles (250-500 A) which is the most abundant and ubiquitous; (3) a profile (F) containing flattened or pleomorphic vesicles; (4) a profile (LSV) containing large oval egg shaped vesicles (750 A); and (5) a pale profile (PP) that contains oval and occasionally pleomorphic vesicles. MSV, SSV, and LSV terminals form asymmetrical contacts and F terminals form symmetrical contacts with both dendritic and vesicle-containing, pale profiles. The vesicle-containing, pale profile is both pre- and post-synaptic and participates in serial synapses. Following unilateral cortical ablations both dark and filamentous degeneration were observed in the ipsilateral basilar pontine gray.
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PMID:The neurons and the synaptic endings in the primate basilar pontine gray. 41 84

Ultrastructure of filamentous contacts was examined in the cat lateral geniculate nucleus. This intercellular contact was classified into two types, asymmetrical and symmetrical, according to its fine structure. (1) The asymmetrical filamentous contact had a different fine structure on the cytoplasmic sides of its apposed membranes. This sort of contact occurred between the postsynaptic components of principal cells and the presynaptic terminals of either optic nerve or interneurons. The membrane on the presynaptic side showed a wavy outline. Plaques of cytoplasmic density were located on the crests of the wave. On the postsynaptic side cytoplasmic dense material formed a regularly arranged latticework on the membrane, 'subjunctional dense lattice'. The dense lattice was closely associated with underlying smooth surfaced endoplasmic reticulum and mitochondria, so as to form a subjunctional complex consisting of these 3 organelles. Two filamentous structures, neurofilaments and microtubules, enter and leave this subjunctional complex. (2) The symmetrical filamentous contact occurred between two principal cell components. Nearly the same fine structural arrangement as that on the postsynaptic side of the asymmetrical contact was present in the cytoplasm on the both sides of this junction.
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PMID:Filamentous contacts containing subjunctional dense lattice and tubular smooth endoplasmic reticulum in cat lateral geniculate nuclei. 57 51

Erythropoietic cells of 5 species, including man, contain endoplasmic reticulum present as individual cisternae or tubules scattered throughout the cytoplasm of all stages except mature RBCs. The endoplasmic reticulum is mainly agranular but occurs frequently as a variant of granular ER which is characterized by an asymmetrical and irregular distribution of ribosomes along one cytoplasmic face. In most cells, the endoplasmic reticulum occurs in close proximity to mitochondria or the plasma membrane , suggesting that the organelle may be involved in functions related to these structures, e.g. haem biosynthesis. Endoplasmic reticulum is more abundant in early than in late erythroid cells. Its exact role in RBC development is unclear. Since endoplasmic reticulum could account for 'plasma membrane-bound ribosomes' reported in lysed reticulocytes, studies were performed which ruled out this possibility and which suggested that such ribosomes were an artifact of the lysing conditions. Hypotonic lysis in less than 20 vol. of magnesium-containing buffers yielded ghosts variably contaminated by ribosomes and other structures. Lysis of reticulocytes in 20-30 vol. of magnesium-free buffer or homogenization of whole cells or crude membrane fractions in hypotonic buffer removed virtually all contaminating ribosomes from the purified membrane fraction.
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PMID:Studies of the endoplasmic reticulum and plasma membrane-bound ribosomes in erythropoietic cells. 67 Mar 18

Bladder biopsies from six boys without a history of urinary tract infection were taken during hypospadias repair operations and examined by electron microscopy. The ultrastructure of the epithelium, which was presumed to represent the normal, is described in detail and compared with the reported findings in other mammalian species. The appearances are generally similar although in our material the luminal membrane of the superficial cells was thicker than that surrounding the other epithelial cells but not asymmetrical. We observed membrane-coating granules which have not been reported before in bladder epithelium. The appearances of the normal bladder are compared to those seen in 24 children with urinary infection. In the presence of acute infection in large heterogeneous secondary lysosomes which are present in the intermediate and superficial cells of the normal bladder are reduced in number and the amount of rough endoplasmic reticulum is increased.
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PMID:An ultrastructural study of the urinary bladder in children correlated with histological, bacteriological, and clinical findings. 112 44

The red nuclei of 14 adult male rats of the Wistar strain were prepared for electron microscopic study following perfusion with a mixture of aldehydes, Neurons of four size categories were identified in 1 mu Epon sections and their ultrastructural characteristics were studied in adjacent thin sections. Giant (greater than 40 mu) and large (26-40 mu) neurons are distinguished primarily by size and possess similar ultrastructural features: extensive areas of rough endoplasmic reticulum (RER), a prominent perinuclear Golgi complex, numerous mitochondria and pigment granules and a large, ovoid nucleus which occasionally contains intranuclear rodlets. Medium size neurons (20-25 mu) have less extensive, poorly organized RER and randomly distributed Golgi complexes. The nuclear envelopes of these cells frequently show multiple invaginations and continuity with the RER cisternae. In small neurons (less than 20 mu) the RER occurs as single or anastomosing strands whi le golgi complexes and pigment granules are few. In both medium size and small neurons, aggregates of condensed chromatin are adherent to the inner nuclear membrane. Three main types of synaptic terminals may be distinguished in the red nucleus: (1) small terminals with flattened vesicles and symmetrical densities (F terminals), (2) small terminals with rounded vesicles and asymmetrical densities (RS terminals), and (3) large (10-15 mu) asymmetrical, rounded vesicle terminals which form multiple contacts along their length (RL terminals). The small neurons receive both F and RS terminals on their dendrites and infrequently on their cell somas. The large and giant neurons receive F, RS and RL terminals on their somas and proximal dendrites and F and RS terminals on their distal dendrites. The somas and dendrites of medium size neurons receive both F and RS terminals but RL terminals do not lie in relation to them. Spine contacts are common throughout the nucleus and occur on both somas and dendrites.
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PMID:An ultrastructural study of the red nucleus in the rat. 115 Sep 26

Using light and electron microscopy the neurons, glial cells and capillaries in hypoglossal nucleus of the rats have been examined up to 20 days after birth. The neuronal nuclei are usually situated ecentrically. The mitochondria and extensively developed Golgi-zones occupy the perinuclear region. The microtubules and lysosomes become more numerous with aging. At the earliest periods rough endoplasmic reticulum (ER) occupies the neuronal periphery, whereas after 14th day it is extended to the perinuclear region also. The ER forms elongated and concentric lamellated bodies and subsurface cisternae. At this time nucleolus like bodies are also numerous in the cytoplasm. After 4th and 6th days the extensive growth of dendrites, containing many cell organelles, and axons rich in microtubules are observed. Only at the birthday do neurons contain glycogen deposit. After 1st day the glycogen leaves the pericaryon, but it persists a long time in the neuronal processes. The symmetrical and asymmetrical contacts are characteristic for the examined period. The axo-somatic and axo-dendritic synapses are more abundant, but "double synapses" are also established. More synaptic boutons possess besides synaptic vesicles dense-core vesicles at the earlier periods. The quantity of asymmetric synapses increases with differentiation. Extensive cell degeneration has been established between 8 and 18th days. At 4 and 6 days the glial cells penetrate from subependymal layer and they have satellite neuronal position. This is more pronounced between 14 and 18 days when the oligodendrocytes are more numerous and active. At the same time fibrous astrocyte like cells are appeared. Microglial cells were not observed. Capillary differentiation, expressed by changes of the endothelial cells, pericytes and connective tissue cells, continues after birth also.
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PMID:[The postnatal development of the hypoglossal nucleus in the rat]. 122 48

One of the hallmarks of Alzheimer pathology is extracellular deposition of beta-amyloid protein (BAP) which is derived from a larger glycoprotein called amyloid precursor protein (APP). Although APP has often been described as a surface membrane protein, such a localization has not previously been demonstrated at the light or electron microscopic level. We now report the results of immunoelectron microscopy using three specific antibodies against different synthetic fragments of APP. All three antibodies demonstrated a major localization to organelles such as the Golgi apparatus, endoplasmic reticulum and vesicular-like structures. A minor proportion of staining with all three was on selective postsynaptic membranes of asymmetrical synapses, whereas staining of presynaptic membranes was not observed. The morphological evidence suggests that one role of APP may be in association with the function of selective synapses.
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PMID:Localization of amyloid precursor protein in selective postsynaptic densities of rat cortical neurons. 128 May 22

Substance P (SP) is a non-opioid peptide that generates a potent analgesia when injected into the periaqueductal gray matter (PAG). The aim of this study was to investigate the fine neuronal structures and synaptic circuits involved in SP action in rats by means of electron microscopy, using immunocytochemical (ICC) pre-embedding methods. A conventional ultrastructural study, carried out to interpret the ICC data correctly, shows small sized nerve cell bodies with a high nucleus-cytoplasmic ratio; absence of an extensive granular endoplasmic reticulum; and few axo-somatic contacts having symmetrical and asymmetrical junctions in equal proportions. The large neuropil is characterized by numerous thin unmyelinated axons and axo-dendritic synapses mainly showing pleomorphic vesicles and asymmetrical junctions. The ICC analysis showed moderately labeled nerve cell bodies with the same structural, synaptic, and dimensional features as the negative cells. In the neuropil SP immunoreactivity is shown by dendrites, synapses, and thin elements which are unidentifiable structurally. No SP terminals synapsing on SP nerve cell bodies were found and only occasional SP light labeled terminals synapsing on negative perikarya were seen. The SP boutons generally have pleomorphic vesicles and asymmetrical junctions. On the basis of these data a possible excitatory activity of PAG SP synapses could be hypothesized. This activity would take place on postsynaptic neurons generally at a dendritic level. Our ultrastructural findings give support to an excitatory role carried out by SP neurons of the PAG, as suggested by the role of PAG circuitry on spinal nociception.
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PMID:Ultrastructure of substance P immunoreactive elements in the periaqueductal gray matter of the rat. 170 83


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