High affinity phlorizin receptor sites and their relation to the glucose transport mechanism in the proximal tubule of dog kidney

1975 ◽  
Vol 394 (1) ◽  
pp. 10-30 ◽  
Author(s):  
Melvin Silverman ◽  
Judith Black
Keyword(s):  
Proximal Tubule ◽  
Glucose Transport ◽  
Transport Mechanism ◽  
High Affinity ◽  
Receptor Sites ◽  
Dog Kidney

scholarly journals Adenosine Receptors of Cerebral Microvessels and Choroid Plexus

1986 ◽  
Vol 6 (4) ◽  
pp. 463-470 ◽  
Author(s):  
Rajesh N. Kalaria ◽  
Sami I. Harik
Keyword(s):  
Cerebral Cortex ◽  
Ligand Binding ◽  
Choroid Plexus ◽  
Adenosine Receptors ◽  
Binding Sites ◽  
Specific Binding ◽  
Cerebral Microvessels ◽  
High Affinity ◽  
Receptor Sites ◽  
Ligand Binding Sites

We studied, by ligand binding methods, the two adenosine receptors, A, and A2, in rat and pig cerebral microvessels and pig choroid plexus. Ligand binding to cerebral microvessels was compared with that to membranes of the cerebral cortex. [3H]Cyclohexyladenosine and [3H]l-phenylisopropyladenosine were the ligands used for A1-receptors, and [3H]5'- N-ethylcarboxamide adenosine ([3H]NECA) was used to assess A2-receptors. We report that cerebral microvessels and choroid plexus exhibit specific [3H]NECA binding, but have no appreciable A1-receptor ligand binding sites. Specific binding of [3H]NECA to cerebral microvessels, choroid plexus, and cerebral cortex was saturable and suggested the existence of two classes of A2-receptor sites: high-affinity ( Kd ∼ 250 n M) and low-affinity ( Kd ∼ 1–2 μ M) sites. The Kd and Bmax of NECA binding to cerebral microvessels and cerebral cortex were similar within each species. Our results, indicating the existence of A2-receptors in cerebral microvessels, are consistent with results of increased adenylate cyclase activity by adenosine and some of its analogues in these microvessels.

THE MEASUREMENT OF HIGH-AFFINITY OESTRADIOL RECEPTORS IN HUMAN UTERINE ENDOMETRIUM AND MYOMETRIUM

1971 ◽  
Vol 68 (3) ◽  
pp. 534-542 ◽  
Author(s):  
D. M. Robertson ◽  
J. Mešter ◽  
J. Beilby ◽  
S. J. Steele ◽  
A. E. Kellie
Keyword(s):  
Menstrual Cycle ◽  
Normal Range ◽  
Biopsy Material ◽  
Uterine Endometrium ◽  
High Affinity ◽  
Biopsy Tissue ◽  
Receptor Sites ◽  
Receptor Concentration ◽  
Human Uterine Endometrium

ABSTRACT The concentration of unoccupied high-affinity oestradiol receptors in the cytosol of human uterine endometrial curettings and biopsy tissue has been determined. In normal specimens, where the day of the menstrual cycle could be assessed histologically, a variation of tissue receptor concentration throughout the cycle was observed showing a maximum at mid-cycle and minima at the beginning and end of the cycle. The distribution of oestradiol receptor sites in the endometrium and myometrium along the length of the uterus has also been studied. Highest concentrations in the endometrium were found in the fundus and these levels fell progressively to negligible concentrations in the isthmus and cervix. In general, the concentration of receptor sites in biopsy material was lower than in curettings and this observation has been related on the region of the uterus from which the samples were obtained. The concentration of receptor sites in abnormal uterine specimens lay within the normal range.

scholarly journals RCO-3 and COL-26 form an external-to-internal module that regulates the dual-affinity glucose transport system in Neurospora crassa

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jinyang Li ◽  
Qian Liu ◽  
Jingen Li ◽  
Liangcai Lin ◽  
Xiaolin Li ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Neurospora Crassa ◽  
Glucose Transport ◽  
Transport System ◽  
Rational Design ◽  
Glucose Sensor ◽  
Glucose Transporters ◽  
Glucose Fluctuation ◽  
High Affinity ◽  
Glucose Transport System

Abstract Background Low- and high-affinity glucose transport system is a conserved strategy of microorganism to cope with environmental glucose fluctuation for their growth and competitiveness. In Neurospora crassa, the dual-affinity glucose transport system consists of a low-affinity glucose transporter GLT-1 and two high-affinity glucose transporters HGT-1/HGT-2, which play diverse roles in glucose transport, carbon metabolism, and cellulase expression regulation. However, the regulation of this dual-transporter system in response to environmental glucose fluctuation is not yet clear. Results In this study, we report that a regulation module consisting of a downstream transcription factor COL-26 and an upstream non-transporting glucose sensor RCO-3 regulates the dual-affinity glucose transport system in N. crassa. COL-26 directly binds to the promoter regions of glt-1, hgt-1, and hgt-2, whereas RCO-3 is an upstream factor of the module whose deletion mutant resembles the Δcol-26 mutant phenotypically. Transcriptional profiling analysis revealed that Δcol-26 and Δrco-3 mutants had similar transcriptional profiles, and both mutants had impaired response to a glucose gradient. We also showed that the AMP-activated protein kinase (AMPK) complex is involved in regulation of the glucose transporters. AMPK is required for repression of glt-1 expression in starvation conditions by inhibiting the activity of RCO-3. Conclusions RCO-3 and COL-26 form an external-to-internal module that regulates the glucose dual-affinity transport system. Transcription factor COL-26 was identified as the key regulator. AMPK was also involved in the regulation of the dual-transporter system. Our findings provide novel insight into the molecular basis of glucose uptake and signaling in filamentous fungi, which may aid in the rational design of fungal strains for industrial purposes.

CHARACTERIZATION AND ASSAY OF THE PROGESTERONE RECEPTOR IN RAT UTERINE CYTOSOL

1978 ◽  
Vol 76 (1) ◽  
pp. 21-31 ◽  
Author(s):  
M. T. VU HAI ◽  
E. MILGROM
Keyword(s):  
Progesterone Receptor ◽  
Receptor Complexes ◽  
High Affinity ◽  
Receptor Sites ◽  
Natural Hormone ◽  
Corticosteroid Binding Globulin ◽  
Steroid Binding Proteins ◽  
Steroid Binding ◽  
High Concentrations ◽  
Synthetic Progestogen

SUMMARY The synthetic progestogen R5020 (17,21-dimethyl-19-norpregna-4,9-diene-3,20-dione) binds with high affinity (Ka = 8·8 × 108 1/mol at 0 °C) to the progesterone receptor from rat uterine cytosol. At nanomolar concentrations, equilibrium is attained in less than 90 min. R5020 has a very low affinity for other specific steroid-binding proteins (corticosteroid-binding globulin and oestrogen receptors) present in relatively high concentrations in the uterine cytosol. The affinity of the receptor for the natural hormone progesterone is remarkably low (Ka= 1 × 108−1·7 × 1081/mol at 0 °C) which explains the instability of progesterone–receptor complexes. Advantage may be taken of this property to remove endogenous progesterone easily by charcoal treatment at 0 °C, a treatment which does not modify the concentration of receptors. A method based on these characteristics is described for the assay of the total number (progesterone-bound and unbound) of receptor sites in uterine cytosol. This assay may be used in various physiological situations where endogenous progesterone is present at unknown concentrations.

ALTERATIONS IN THE GLUCOSE TRANSPORT MECHANISM IN PATIENTS WITH COMPLICATIONS OF BACTERIAL MENINGITIS

PEDIATRICS ◽  
1964 ◽  
Vol 34 (4) ◽  
pp. 491-502
Author(s):  
R. D. Brooke Williams
Keyword(s):  
Cerebrospinal Fluid ◽  
Bacterial Meningitis ◽  
Glucose Transport ◽  
Intravenous Injection ◽  
Transport Mechanism ◽  
Spinal Fluid ◽  
Normal Pattern ◽  
The Third ◽  
Glucose Diffusion

Glucose diffusion tests were made on 8 children with bacterial meningitis, in 7 [SEE TABLE IV AND FIG 8. IN SOURCE PDF] of whom the organism had been identified. The results of the tests were correlated with the outcome of the illness. Of 3 patients who recovered without sequelae the glucose diffusion patterns were normal in 2 cases, while the third case had somewhat low curves. In 4 cases of proven bacterial meningitis with complication all the tests were abnormal. Three of these were cases of proven hydrocephalus and there was a reversal of the normal pattern of diffusion for the entry of glucose into the cisternal and lumbar regions. An actual lowering of the cisternal glucose following the intravenous injection of glucose was observed in two cases with initial very low spinal fluid sugars. The hypothesis is proposed that alterations in the blood cerebrospinal fluid barrier perhaps due to increased metabolism of arachnoid lining cells or edema in [SEE FIG 9 IN SOURCE PDF] addition to the action of bacteria and leukocytes contribute to the persistent hypoglycorrhachia seen in complicated cases of bacterial meningitis.

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