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)

The homogeneous, single-walled phosphatidylcholine-cholesterol mixed vesicles were prepared by ultrasonic irradiation of egg phosphatidylcholine in the presence of various amounts of cholesterol in solution at 4 degrees under a nitrogen atmosphere followed by molecular sieve chromatography on a Sepharose 4B column. Physicochemical studies performed on these systems invluding sedimentation velocity, diffusion, partial specific volume, intrinsic viscosity, and trapped volume measurements allowed estimation of the weight-average vesicle weight, the vesicle shape, and bilayer membrane thickness of the binary mixture of phosphatidylcholine and cholesterol. Vesicle hydration was calculated using two different methods and the agreement between them was excellent up to cholesterol concentration of 0.32 mole fraction. It was observed that the structural parameters change slowly with increasing cholesterol content up to around 0.3 mole fraction and a relatively abrupt structural alteration occurs above this cholesterol content. This abrupt structural change is consistent with the asymmetrical distribution of lipid composition between the inner and outer bilayer face.
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PMID:Structural studies on phophatidylcholine-cholesterol mixed vesicles. 117 Aug 90

In 1979 Cohen et Hayden and in 1983 Wiedemann et al. delineated a syndrome consisting of partial gigantism of the hands and/or feet, nevi, hemihypertrophy, subcutaneous tumors, macrocephaly or other skull anomalies and possible accelerated growth and visceral affections. Hitherto the literature pertaining to this syndrome consists of somewhat more than 100 cases of which some, that have been described previously or subsequently under other headings, were rediagnosed as being Proteus syndromes. Of these, more than half show vascular anomalies closely resembling those observed in the Klippel-Trenaunay syndrome, but in the Proteus syndrome appear to be more haphazardly distributed over the integument. We report 3 pediatric patients with the Proteus syndrome, all showing cutaneous angiodysplasias. These patients were initially diagnosed as suffering from "severe or atypical Klippel-Trenaunay syndrome". In one of these, cardiac tumors were observed soon after birth which subsequently showed spontaneous involution and were therefore considered to be rhabdomyomas. In the Proteus syndrome cardiac pathology is rare, and cardiac tumors have not been described previously. Moreover, we observed umbilical hernia in two of our patients, a feature which has hitherto not been reported in patients with the Proteus syndrome. In all our patients a broad thoracic cage resembling a "body-builders chest", asymmetrical and disproportional macrodactyly and broad, flat feet were conspicuous. These broad, flat feet with macrodactyly and large spaces between the first and second digits were designed by the parents of one of our patient as "chimpanzee's feet". Macrodactyly, "chimp's" feet and a broad thoracic cage are considered by us to be clinical hallmarks of the Proteus syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Proteus syndrome. Expansion of the phenotype. Apropos of 3 pediatric cases]. 133 4

Open-channel ion permeation properties were investigated for Ca++-activated K+ (CaK) channels in solutions of K+ and its analogues T1+, Rb+, and NH4+. Single CaK channels were inserted into planar lipid bilayers composed of neutral phospholipids, and open-channel current-voltage (I-V) relations were measured in symmetrical and asymmetrical solutions of each of these individual ions. For all concentrations studied, the zero-voltage conductance falls in the sequence K+ greater than T1+ greater than NH4+ greater than Rb+. The shape of the I-V curve in symmetrical solutions of a single permeant ion is non-ohmic and is species-dependent. The I-V shape is sublinear for K+ and T1+ and superlinear for Rb+ and NH4+. As judged by reversal potentials under bi-ionic conditions with K+ on one side of the bilayer and the test cation on the other, the permeability sequence is T1+ greater than K+ greater than Rb+ greater than NH4+ at 300 mM, which differs from the conductance sequence. Symmetrical mixtures of K+ or NH4+ with Rb+ show a striking anomalous mole fraction behavior, i.e., a minimum in single-channel conductance when the composition of a two-ion mixture is varied at constant total ion concentration. This result is incompatible with present models that consider the CaK channel a single-ion pore. In total, the results show that the CaK channel finely discriminates among K+-like ions, exhibiting different energy profiles among these species, and that several such ions can reside simultaneously within the conduction pathway.
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PMID:Multi-ion conduction and selectivity in the high-conductance Ca++-activated K+ channel from skeletal muscle. 243 47

Batrachotoxin-modified, voltage-dependent sodium channels from canine forebrain were incorporated into planar lipid bilayers. Single-channel conductances were studied for [Na+] ranging between 0.02 and 3.5 M. Typically, the single-channel currents exhibited a simple two-state behavior, with transitions between closed and fully open states. Two other conductance states were observed: a subconductance state, usually seen at [NaCl] greater than or equal to 0.5 M, and a flickery state, usually seen at [NaCl] less than or equal to 0.5 M. The flickery state became more frequent as [NaCl] was decreased below 0.5 M. The K+/Na+ permeability ratio was approximately 0.16 in 0.5 and 2.5 M salt, independent of the Na+ mole fraction, which indicates that there are no interactions among permeant ions in the channels. Impermeant and permeant blocking ions (tetraethylammonium, Ca++, Zn++, and K+) have different effects when added to the extracellular and intracellular solutions, which indicates that the channel is asymmetrical and has at least two cation-binding sites. The conductance vs. [Na+] relation saturated at high concentrations, but could not be described by a Langmuir isotherm, as the conductance at low [NaCl] is higher than predicted from the data at [NaCl] greater than or equal to 1.0 M. At low [NaCl] (less than or equal to 0.1 M), increasing the ionic strength by additions of impermeant monovalent and divalent cations reduced the conductance, as if the magnitude of negative electrostatic potentials at the channel entrances were reduced. The conductances were comparable for channels in bilayers that carry a net negative charge and bilayers that carry no net charge. Together, these results lead to the conclusion that negative charges on the channel protein near the channel entrances increase the conductance, while lipid surface charges are less important.
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PMID:Batrachotoxin-modified sodium channels in planar lipid bilayers. Ion permeation and block. 244 Sep 77

Differential oxygen binding measurements obtained over the pH range 6.95 to 9.10 at 25 degrees C have allowed a detailed description of the alkaline Bohr effect of human hemoglobin Ao. Phenomenological analysis of the data in terms of the Adair equation shows that: (1) the oxygen binding curves are asymmetrical with the population of the triply oxygenated species being negligible throughout the pH range studied: (2) the shape of the oxygen binding curve is affected by pH, especially at low saturation; and (3) the maximum O2-proton linkage is -0.52 mole of proton per mole of oxygen at pH 7.4. A possible molecular mechanism of the Bohr effect is proposed within the framework of an allosteric model which accounts for the low population of triply oxygenated hemoglobin species. At least three Bohr groups are necessary for a quantitative description of the alkaline Bohr effect. Two of these groups titrate in the range of the His146 beta and Vall alpha residues, which have long been identified as the main alkaline Bohr groups, and altogether contribute 84% of the alkaline Bohr effect at physiological pH. A third ionizable group, linked to oxygenation presumably at the beta chains, is implicated and is titrated in a pH range characteristic of a surface histidyl residue.
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PMID:Alkaline Bohr effect of human hemoglobin Ao. 284 May 10

Eight cases of cutis marmorata telangiectatica congenita are presented and an analysis of associated alterations on seven is done. These abnormalities are mainly asymmetrical body development (hypotrophy of the leg in two cases, hemihypertrophy of body in five), hemihypertrophy of brain with psychomotor retardation in three patients, Nevus flameus on lumbar region in one and syndactylies on hands and feet in one. Inclusion of the disease into neurocutaneous syndromes is suggested and is emphasized the importance of the pediatric and neurological follow-up of these patients.
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PMID:[Cutis marmorata telangiectatica congenita. Associated abnormalities]. 1008 60

Differential binding curve measurements for oxygen in the presence of fixed carbon dioxide activities have allowed a detailed determination of the linkage between carbon dioxide and the oxygenated intermediates of human hemoglobin. Model-independent analysis of the data shows that at pH 7.4: (1) the oxygen binding curves are asymmetrical, the population of the triply oxygenated species being negligible; (2) the shape of the oxygen binding curve is invariant with carbon dioxide activity; (3) the maximum linkage is -0.32 moles carbon dioxide per mole oxygen; and (4) the overall carbon dioxide-dependent shift in the oxygen binding curve cannot be explained in terms of carbamino formation alone, the additional influence of bicarbonate being required. An allosteric model that accounts for the low population of triply oxygenated hemoglobin species is employed here as a framework from which to explore the carbon dioxide linkage mechanism at the intermediate stages of oxygenation. Carbon dioxide binding constants are found to be 780 M-1 and 580 M-1 for carbon dioxide binding to the deoxygenated alpha and beta chains, respectively, and 150 M-1 for carbon dioxide binding to the oxygenated form of both chains, as determined by simultaneous fitting of the oxygen binding curves with the model. Finally, by use of the determined binding polynomial for the carbon dioxide-oxygen linkage scheme, we have constructed a series of linkage graphs.
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PMID:Carbon dioxide and oxygen linkage in human hemoglobin tetramers. 311 59

The recognition of atypical or dysplastic nevomelanocytic nevi potentially provides clinicians with another means of identifying individuals at increased risk for cutaneous malignant melanoma. However, a great deal of controversy still surrounds these lesions, their significance, and the clinical and histologic criteria needed for their diagnosis at present. In general, dysplastic nevi tend to be asymmetrical and larger (greater than 5 mm) than ordinary acquired nevi, have a macular component, irregular and ill-defined borders, and haphazard (variegate) coloration. A clinical diagnosis of dysplastic nevi must be confirmed by histopathology, since not all clinically atypical nevi are dysplastic. While precise histopathologic criteria for dysplastic nevi are lacking, most authorities agree that an abnormal nevomelanocytic proliferative pattern as manifested by increased numbers of basilar melanocytes and/or abnormal junctional nevomelanocytic nesting in the setting of lentiginous epidermal hyperplasia, variable degrees of nevomelanocytic nuclear atypia, and a lymphocytic host response are consistent with a histologic diagnosis of dysplastic nevi. Current data for individuals with dysplastic nevi and a family history of cutaneous malignant melanoma (at least two family members with cutaneous malignant melanoma) indicate a relative risk for cutaneous malignant melanoma about 148 times that of the general population. In comparison, cutaneous malignant melanoma risk seems lower for individuals with familial dysplastic nevi (but without familial cutaneous malignant melanoma) and "sporadic" dysplastic nevi. With respect to progression to melanoma, probably the vast majority of dysplastic nevi remain stable or possibly regress. Management of individuals with histologically confirmed dysplastic nevi involves periodic skin examinations. Regional overview and life-size photography are helpful in following these patients. Patients should also be instructed in the examination of their own skin. While a definite relationship between sun exposure and dysplastic nevi remains unproved, the use of sunscreens and avoidance of unnecessary sun exposure are advised. Examination of family members for atypical melanocytic lesions is also recommended.
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PMID:The dysplastic nevus: recognition and management. 327 48

The tyrosyl-tRNA synthetase from Bacillus stearothermophilus crystallizes as a symmetrical dimer with each subunit having a complete active site. The enzyme-substrate complexes, however, are known to be asymmetrical in solution because the enzyme exhibits half-of-the-sites activity by binding tightly only 1 mol of tyrosine or 1 mol of tyrosyl adenylate per mole of dimer. Evidence is now presented that the unligated enzyme is also asymmetrical in solution. Symmetry was investigated by construction of heterodimers containing one full-length subunit and one truncated subunit, allowing the introduction of different mutations into each monomer. Each dimer is active at only one site, but the site used is randomly distributed between the subunits. Each heterodimer thus consists of two equal populations, one activating tyrosine at a full-length subunit and the other at the truncated subunit. No detectable interconversion is found between active and inactive sites over several minutes either in the absence of substrates or when the enzyme is turning over in the steady state. Kinetic evidence implies that wild-type enzyme is inherently asymmetrical even in the absence of substrate.
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PMID:Asymmetry of tyrosyl-tRNA synthetase in solution. 336 65

The case of a 5-month-old black female child with a linear sebaceous naevus syndrome and multiple congenital anomalies is presented. Ocular malformations consisted of colobomatous changes of the lid and retina, dermoid of the conjunctiva, chorioretinal changes, and peripapillary atrophy of the optic nerve. Systemic findings included midline cleft of the secondary palate with involvement by the naevus, bilateral hearing loss, asymmetrical skull bones, ventricular septal defect, epidermal inclusion cyst, and developmental delay without seizures.
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PMID:Ocular findings in linear sebaceous naevus syndrome. 358 Mar 38


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