scholarly journals Chicken FK506-binding protein, FKBP65, a member of the FKBP family of peptidylprolyl cis–trans isomerases, is only partially inhibited by FK506

1998 ◽  
Vol 330 (1) ◽  
pp. 109-114 ◽  
Author(s):  
Baifei ZENG ◽  
J. Randy MACDONALD ◽  
G. James BANN ◽  
Konrad BECK ◽  
E. Jay GAMBEE ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cyclosporin A ◽  
Rough Endoplasmic Reticulum ◽  
Analytical Ultracentrifugation ◽  
Specific Activity ◽  
Binding Protein ◽  
Type Iii Collagen ◽  
Fk506 Binding Protein ◽  
Endoplasmic Reticulum Protein

The chicken FK506-binding protein FKBP65, a peptidylprolyl cis-trans isomerase, is a rough endoplasmic reticulum protein that contains four domains homologous to FKBP13, another rough endoplasmic reticulum PPIase. Analytical ultracentrifugation suggests that in FKBP65 these four domains are arranged in a linear extended structure with a length of about 26 nm and a diameter of about 3 nm. All four domains are therefore expected to be accessible to substrates. The specificity of FKBP65 towards a number of peptide substrates was determined. The specific activity of FKBP65 is generally lower than that of FKBP12 when expressed as a per domain activity. The substrate specificity of FKBP65 also differs from that of FKBP12. Inhibition studies show that only one of the four domains can be inhibited by FK506, a powerful inhibitor of all other known FKBPs. Furthermore, the same domain seems to be susceptible to inhibition by cyclosporin A. No other FKBPs were shown to be inhibited by cyclosporin A. It is also shown that FKBP65 can catalyse the re-folding of type III collagen in vitro with a kcat/Km = 4.3×103 M-1·s-1.

scholarly journals The Rough Endoplasmic Reticulum-resident FK506-binding Protein FKBP65 Is a Molecular Chaperone That Interacts with Collagens

2008 ◽  
Vol 283 (46) ◽  
pp. 31584-31590 ◽  
Author(s):  
Yoshihiro Ishikawa ◽  
Janice Vranka ◽  
Jackie Wirz ◽  
Kazuhiro Nagata ◽  
Hans Peter Bächinger
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Molecular Chaperone ◽  
Binding Protein ◽  
Fk506 Binding Protein

scholarly journals FK506-binding protein 5 promotes the progression of papillary thyroid carcinoma

2021 ◽  
Vol 49 (4) ◽  
pp. 030006052110083
Author(s):  
Zhenya Gao ◽  
Fang Yu ◽  
Huanxia Jia ◽  
Zhuo Ye ◽  
Shijie Yao
Keyword(s):  
Papillary Thyroid Carcinoma ◽  
Thyroid Carcinoma ◽  
Binding Protein ◽  
Progression Free Survival ◽  
Papillary Thyroid ◽  
Expression Levels ◽  
Fk506 Binding Protein ◽  
Normal Tissues ◽  
Induced Apoptosis

Objective To detect the expression of FK506-binding protein 5 (FKBP5) in human papillary thyroid carcinoma (PTC) tissues, and explore its possible role in the progression of PTC. Methods FKBP5 expression levels were assessed in 115 PTC tissues and corresponding normal tissues by immunohistochemistry. We also examined the correlations between FKBP5 expression and clinicopathological factors and survival in 75 patients with PTC. The effects of FKBP5 on the proliferation and apoptosis of PTC cells were detected by colony-formation, MTT, and flow cytometry assays, respectively. We further investigated the effects of FKBP5 on tumor growth in mice. Results We revealed high expression levels of FKBP5 in human PTC tissues compared with normal tissues. Furthermore, high FKBP5 expression was associated with an increased incidence of intraglandular dissemination, and lower overall and progression-free survival. FKBP5 depletion remarkably suppressed the proliferation and induced apoptosis of PTC cells in vitro. FKBP5 further contributed to the growth of PTC tumors in mice. Conclusions The results of this study demonstrated the potential involvement of FKBP5 in the progression of PTC, and confirmed FKBP5 as a novel therapeutic target for PTC treatment.

scholarly journals EDEM2 stably disulfide-bonded to TXNDC11 catalyzes the first mannose trimming step in mammalian glycoprotein ERAD

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ginto George ◽  
Satoshi Ninagawa ◽  
Hirokazu Yagi ◽  
Taiki Saito ◽  
Tokiro Ishikawa ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Gene Knockout ◽  
Covalent Bonding ◽  
Cxxc Motif ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Endoplasmic Reticulum Protein ◽  
Hct116 Cells

Sequential mannose trimming of N-glycan (Man9GlcNAc2 -> Man8GlcNAc2 -> Man7GlcNAc2) facilitates endoplasmic reticulum-associated degradation of misfolded glycoproteins (gpERAD). Our gene knockout experiments in human HCT116 cells have revealed that EDEM2 is required for the first step. However, it was previously shown that purified EDEM2 exhibited no α1,2-mannosidase activity toward Man9GlcNAc2 in vitro. Here, we found that EDEM2 was stably disulfide-bonded to TXNDC11, an endoplasmic reticulum protein containing five thioredoxin (Trx)-like domains. C558 present outside of the mannosidase homology domain of EDEM2 was linked to C692 in Trx5, which solely contains the CXXC motif in TXNDC11. This covalent bonding was essential for mannose trimming and subsequent gpERAD in HCT116 cells. Furthermore, EDEM2-TXNDC11 complex purified from transfected HCT116 cells converted Man9GlcNAc2 to Man8GlcNAc2(isomerB) in vitro. Our results establish the role of EDEM2 as an initiator of gpERAD, and represent the first clear demonstration of in vitro mannosidase activity of EDEM family proteins.

scholarly journals Separation of the Binding Step from the Collagen Platelet Reaction

1977 ◽  
Author(s):  
P.L. Kronick ◽  
S.A. Jimenez
Keyword(s):  
Type I Collagen ◽  
Specific Activity ◽  
Adenine Nucleotides ◽  
High Specific Activity ◽  
Type Iii Collagen ◽  
Type I ◽  
Type Iii ◽  
Valid Comparison ◽  
Platelet Reaction

Determination of activity of most agents in stimulating platelets to aggregate or release adenine nucleotides is conveniently done by titrating the platelet reaction with the agent. Platelets have previously been titrated with different types of collagen (types I, II, and III) in this way to compare the activities of the collagens. It has been concluded that the order of activity is type III>I>II. Whether this order is due to differences in binding was not obvious from these experiments because the binding was not determined directly. We have developed a method of comparing activities by measuring the targeted dose for each point in the titration - the amount of collagen which actually binds to platelets. The collagens used in these experiments were prepared in vitro from embryonic chick tissue to give labelled products of extremely high specific activity without structural alteration. We find that type I collagen is at least 20 times as active as previously reported, and that the activity of Type III collagen is not significantly higher when the amounts bound are taken into account. The fraction of the labelled tendon collagen which was bound to platelets was identified as type I by its hydroxyproline/proline ratio. Direct measurement of the bound fraction in dose-response studies is required for valid comparison of collagen activities.

scholarly journals LECITHIN SYNTHESIS, INTRACELLULAR TRANSPORT, AND SECRETION IN RAT LIVER

1969 ◽  
Vol 40 (2) ◽  
pp. 461-483 ◽  
Author(s):  
Olga Stein ◽  
Yechezkiel Stein
Keyword(s):  
Endoplasmic Reticulum ◽  
Liver Cell ◽  
Phosphatidyl Choline ◽  
Intracellular Transport ◽  
Phosphatidyl Ethanolamine ◽  
Specific Activity ◽  
Perfused Liver ◽  
Precursor Pool

Injection of choline-3H into choline-deficient rats resulted in an enhanced incorporation of the label into liver lecithin, as compared to the incorporation of label into liver lecithin of normal rats. The results obtained with the use of different lecithin precursors indicate that in the intact liver cell, both in vivo and in vitro, exchange of choline with phosphatidyl-choline is not significant. The synthesis and secretion of lecithins by the choline-deficient liver compare favorably with the liver of choline-supplemented rats, when both are presented with labeled choline or lysolecithin as lecithin precursors. Radioautography of the choline-deficient liver shows that 5 min after injection of choline-3H the newly synthesized lecithin is found in the endoplasmic reticulum (62%), mitochondria (13%), and at the "cell boundary" (20%). The ratio of the specific activity of microsomal and mitochondrial lecithin, labeled with choline, glycerol, or linoleate, was 1.53 at 5 min after injection, but the ratio of the specific activity of phosphatidyl ethanolamine (PE), labeled with ethanolamine, was 5.3. These results indicate that lecithin and PE are synthesized mainly in the endoplasmic reticulum, and are transferred into mitochondria at different rates. The site of a precursor pool of bile lecithin was studied in the intact rat and in the perfused liver. Following labeling with choline-3H, microsomal lecithin isolated from perfused liver had a specific activity lower than that of bile lecithin, but the specific activity of microsomal linoleyl lecithin was comparable to that of bile lecithin between 30 and 90 min of perfusion. It is proposed that the site of the bile lecithin pool is located in the endoplasmic reticulum and that the pool consists mostly of linoleyl lecithin.

Phosphatidylethanolamine in Liver Mitochondria and Endoplasmic Reticulum; Molecular Species Distribution and Turnover

1975 ◽  
Vol 53 (6) ◽  
pp. 698-705 ◽  
Author(s):  
J. G. Parkes ◽  
W. Thompson
Keyword(s):  
Endoplasmic Reticulum ◽  
Fatty Acid ◽  
Specific Activity ◽  
Liver Mitochondria ◽  
Relative Activity ◽  
Layer Chromatography ◽  
Kinetics Of ◽  
Fatty Acid Compositions

Phosphatidylethanolamine from mitochondria and microsomes of guinea pig liver was separated by thin-layer chromatography into eight different classes differing in degree of unsaturation. The fatty acid compositions and molar proportions of each class isolated from microsomes were very similar to the corresponding class in mitochondria. In both organelles about half of the total was dienoic species while tetraenes comprised approximately 20%. Stearic acid was the major saturated fatty acid and in each membrane a greater selectivity for stearate over palmitate was found in each sub-class of phosphatidylethanolamine, when compared with the corresponding class of phosphatidylcholine.Following the intraperitoneal injection of [2-3H]glycerol, the labelling of each molecular class of phosphatidylethanolamine showed very similar progressions in microsomes and mitochondria over a 3 h interval. In both organelles the highest relative specific activity was attained by penta-plus hexaenoic classes, while the large dienoic class had the lowest relative activity, which, however, increased with time. Analysis of the dienoic class of phosphatidylethanolamine from whole liver showed it to be constituted by a rapidly turning over palmitoyl–linoleoyl fraction and a slowly labelled stearoyl–linoleoyl fraction, a pattern also exhibited by dienoic phosphatidylcholines.The similarities in profile of molecular classes of phosphatidylethanolamine and in the kinetics of labelling in vivo point to a close metabolic relation between the lipids of both organelles, suggestive of a transfer of different molecular classes at comparable rates from the endoplasmic reticulum, the site of synthesis, to the mitochondria. This is consistent with numerous other studies in vitro that have demonstrated inter-organelle exchange of lipids.

scholarly journals FK506 Binding Protein from a Thermophilic Archaeon,Methanococcus thermolithotrophicus, Has Chaperone-like Activity in Vitro

Biochemistry ◽  
2000 ◽  
Vol 39 (10) ◽  
pp. 2822-2822 ◽  
Author(s):  
Masahiro Furutani ◽  
Akira Ideno ◽  
Toshii Iida ◽  
Tadashi Maruyama
Keyword(s):  
Binding Protein ◽  
Methanococcus Thermolithotrophicus ◽  
Fk506 Binding Protein ◽  
Thermophilic Archaeon

scholarly journals RADIOAUTOGRAPHIC VISUALIZATION OF THE INCORPORATION OF GALACTOSE-3H AND MANNOSE-3H BY RAT THYROIDS IN VITRO IN RELATION TO THE STAGES OF THYROGLOBULIN SYNTHESIS

1969 ◽  
Vol 43 (2) ◽  
pp. 289-311 ◽  
Author(s):  
P. Whur ◽  
Annette Herscovics ◽  
C. P. Leblond
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Light Microscope ◽  
Detectable Effect ◽  
Apical Vesicles ◽  
Rat Thyroid

Rat thyroid lobes incubated with mannose-3H, galactose-3H, or leucine-3H, were studied by radioautography. With leucine-3H and mannose-3H, the grain reaction observed in the light microscope is distributed diffusely over the cells at 5 min, with no reaction over the colloid. Later, the grains are concentrated towards the apex, and colloid reactions begin to appear by 2 hr. With galactose-3H, the reaction at 5 min is again restricted to the cells but it consists of clumped grains next to the nucleus. Soon after, grains are concentrated at the cell apex and colloid reactions appear in some follicles as early as 30 min. Puromycin almost totally inhibits incorporation of leucine-3H and mannose-3H, but has no detectable effect on galactose-3H incorporation during the 1st hr. Quantitation of electron microscope radioautographs shows that mannose-3H label localizes initially in the rough endoplasmic reticulum, and by 1–2 hr much of this reaction is transferred to the Golgi apparatus. At 3 hr and subsequently, significant reactions are present over apical vesicles and colloid, while the Golgi reaction declines. Label associated with galactose-3H localizes initially in the Golgi apparatus and rapidly transfers to the apical vesicles, and then to the colloid. These findings indicate that mannose incorporation into thyroglobulin precursors occurs within the rough endoplasmic reticulum; these precursors then migrate to the Golgi apparatus, where galactose incorporation takes place. The glycoprotein thus formed migrates via the apical vesicles to the colloid.

The biosynthesis of cytochrome P450 by rough endoplasmic reticulum in vitro

FEBS Letters ◽  
1979 ◽  
Vol 98 (2) ◽  
pp. 403-407 ◽  
Author(s):  
John A. Craft ◽  
Michael B. Cooper ◽  
Margaret R. Estall ◽  
Brian R. Rabin
Keyword(s):  
Endoplasmic Reticulum ◽  
Cytochrome P450 ◽  
Rough Endoplasmic Reticulum
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