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PubMed2004

Low-dose continuous iron therapy leads to a positive iron balance and decreased serum transferrin levels in chronic haemodialysis patients.

BACKGROUND: Iron balance is critical for adequate erythropoiesis, but its optimal therapeutic regimen remains to be defined. Continuous maintenance therapy with iron has been proposed for dialysis patients on recombinant human erythropoietin (rHuEpo) in the hope that the regimen is adequate and safe. METHODS: We determined serum ferritin, transferrin, transferrin saturation (TSAT), serum transferrin receptors, albumin and C-reactive protein (CRP) in a 3-year prospective study in 30 chronic haemodialysis patients on dialysis treatment for 132+/-111 months (18 males, 12 females; mean age 56+/-14 years). Beginning in the year 2000, they regularly received low-dose maintenance iron supplementation (i.v. iron gluconate 31.25 mg/week) for 12 months (Period 1 or first treatment phase), followed by a 6-month withdrawal (Period 2 or stop phase) and then by continuous maintenance iron therapy (i.v. iron gluconate 31.25 mg/week) for another 9 months (Period 3 or re-challenge phase). RESULTS: A significant increase in serum ferritin and TSAT was observed, with values exceeding 500 ng/ml and 50% in 10/30 (33%) and 7/30 (23%) of subjects, respectively, in Period 1, and in 11 and 5% in Period 3. A significant decrease in serum transferrin was documented during Period 1, followed by an increase in Period 2 and a decrease in Period 3. Serum albumin remained stable. Serum transferrin was always negatively correlated with ferritin (r = -0.41, P<0.001) and weakly correlated with serum transferrin receptors (r = 0.178, P<0.05), but was not correlated with serum albumin or CRP. Regression equations based on pre-treatment serum ferritin values were developed for predicting the value of serum ferritin at any time following the beginning of continuous iron supplementation. They fitted a linear relationship for males (y = 81 + 21.5 x time) and for females (y = 65 + 22 x time). Percentile charts for quantitative tracking of serum ferritin increases and decreases in patients have also been developed from values measured at different times. These charts show box-plot distributions of expected ferritin against time. CONCLUSIONS: Even continuous low-dose maintenance iron therapy, with only 31.25 mg weekly over 1 year, cannot prevent the risk of iron overload in patients with moderate anaemia. Furthermore, this treatment is responsible for decreases in serum transferrin, unrelated to changes in serum albumin, possibly of concern for hypo-transferrinaemia as an independent risk factor for iron toxicity.

Aged↗
PubMed2001

Molecular evolution of transferrin: evidence for positive selection in salmonids.

Transferrins are iron-binding proteins that are involved in iron storage and resistance to bacterial disease. Previous work has shown that nonsynonymous-to-synonymous-site substitution ratios (d(n)/d(s) ratios) between transferrin genes from some salmonid species were significantly greater than 1.0, providing evidence for positive selection at the transferrin gene. The purpose of the current study was to put these earlier results in a broader evolutionary context by examining variation among 25 previously published transferrin sequences from fish, amphibians, and mammals. The results of the study show that evidence for positive selection at transferrin is limited to salmonids-d(n)/d(s) ratios estimated for nonsalmonid lineages were generally less than 1.0. Within the salmonids, approximately 13% of the transferrin codon sites are estimated to be subject to positive selection, with an estimated d(n)/d(s) ratio of approximately 7. The three- dimensional locations of some of the selected sites were inferred by comparing these sites to homologous sites in the bovine lactoferrin crystallographic structure. The selected sites generally fall on the outside of the molecule, within and near areas that are bound by transferrin-binding proteins from human pathogenic bacteria. The physical locations of sites estimated to be subject to positive selection support previous speculation that competition for iron from pathogenic bacteria could be the source of positive selection.

Amino Acid Substitution↗
PubMed2001

Role of the transcriptional coactivator CBP/p300 in linking basic helix-loop-helix and CREB responses for follicle-stimulating hormone-mediated activation of the transferrin promoter in Sertoli cells.

Sertoli cells are the epithelial cells responsible for the onset of pubertal development and the maintenance of spermatogenesis in the adult. Transferrin is one of the major secretory products expressed by differentiated Sertoli cells. Investigation of the transcriptional control of transferrin gene expression provides insight regarding the regulation of Sertoli cell differentiation. The optimal activation of the mouse transferrin promoter (mTf) by FSH requires the synergistic actions of the cAMP response element-binding protein (CREB) binding to the cAMP response element-like proximal region II (PRII) and the basic helix-loop-helix (bHLH) binding to the E-box. Proximal region II alone is sufficient for cAMP-mediated activation. The proximity of the PRII and E-box (220 base pairs apart) suggests the possibility of interaction between CREB and bHLH proteins. Such an interaction can be mediated by transcriptional integrators such as CREB-binding protein (CBP) and/or p300 and may stabilize the binding of trans-acting factors to their respective cis-elements. Such an interaction may also provide a mechanism for cell-specific promoter activation. The hypothesis tested in this study was that CBP/p300 is required for the synergistic activation of the transferrin promoter involving PRII and E-box through the formation of a ternary complex. In the Sertoli cells, both CBP and p300 proteins are expressed. The effect of CBP/p300 on transferrin promoter activation and, hence, Sertoli cell function was studied by using antisense oligonucleotides (AS-oligo). In the presence of CBP/p300 AS-oligo, activity of the FSH-induced mTf-chloramphenicol acetyl transferase (CAT) was significantly lower as compared to the respective controls. Interestingly, AS-oligo had no effect on cAMP-induced activation of the transferrin promoter reporter construct (mTf-CAT). Mutations in the E-box (EB*) significantly reduced the FSH response. The presence of AS-oligo had no further effect on the FSH-mediated activation of the EB*-mTf-CAT construct but reduced cAMP-mediated activation. Mutations in the CRE-like PRII (PRII*) also significantly reduced the FSH response. Activation of the PRII*-mTf-CAT in response to cAMP was completely abolished. The presence of AS-oligo had no further effect on the FSH- or cAMP-mediated activation of the PRII*-mTf-CAT construct. In Sertoli cells, CBP/p300 was coimmunoprecipitated with CREB and the bHLH protein E47. These observations suggest that CBP/p300 appears to be involved in regulating FSH-mediated activation of the transferrin promoter by linking bHLH and CREB activities.

Animals↗
PubMed1993

Ethanol enhances desialylation of transferrin by liver endothelial cells in the rat.

Desialylated transferrin is emerging as a reliable index of alcoholism, and liver endothelial cells are known to partially desialylate transferrin. The effect of a single intraperitoneal injection of ethanol on the desialylation of transferrin in the rat was studied. In pulse-chase experiments, fully sialylated diferric transferrin labeled with 125I (protein moiety) or 3H (sialyl residues) was incubated with isolated, fractionated liver endothelial cells from rats that were given ethanol. The supernatants then were subjected to column chromatography using RCA120-agarose to separate and quantify the desialylated fraction of transferrin. Saline-treated animals served as controls. Incubation of the endothelial cells derived from the liver of ethanol-treated rats resulted in a 263% increase in desialylation level of transferrin. Our data indicate that administering ethanol in rats enhances the desialylation of transferrin by rat liver endothelial cells.

Animals↗
PubMedDate not supplied

The influence of gestational age, size for dates, and prenatal steroids on cord transferrin levels in newborn infants.

Serum transferrin levels assess protein status in older children and adults. To generate standards for its use in newborn infants, we measured umbilical cord serum transferrin levels in 161 appropriate (AGA), 25 large (LGA) and 16 small (SGA) for gestational age infants between 25 and 43 weeks' gestation. We also assessed the effects of intrauterine growth, exposure to prenatal steroids, and presence of pulmonary maturity on neonatal transferrin levels. Cord transferrin levels in AGA infants were significantly correlated with increasing gestational age (r = 0.60; p less than 0.001). Infants born before 37 weeks' gestation had significantly lower transferrin levels, when compared with those born at term (p less than 0.001). LGA infants had significantly higher levels than age-matched AGA infants (253 +/- 75 vs. 214 +/- 53 mg/dl; p less than 0.025). Despite significantly lower mean birth weights (p less than 0.001), SGA infants also had significantly higher levels than gestational age-matched AGA controls (227 +/- 63 vs. 167 +/- 40 mg/dl; p less than 0.005). For infants less than 35 weeks' gestation, neither the 20 preterm infants with exposure to prenatal steroids (maternal betamethasone), nor the 26 infants with pulmonary maturity had significantly elevated transferrin levels, when compared with gestational age-matched control infants. Newborn transferrin levels correlate well with gestational age and are significantly affected by size for dates, but not by a brief course of prenatal steroids or by pulmonary maturity.

Betamethasone↗
PubMed2004

Induction of transferrin receptor by ethanol in rat primary hepatocyte culture.

BACKGROUND: It is not uncommon for alcoholics to have iron accumulation in the liver, a condition that may contribute to the development of alcoholic liver disease. Recently, we reported that the expression of transferrin receptor, which mediates cellular iron uptake, was increased in hepatocytes in patients with alcoholic liver disease. To elucidate the mechanism of the iron accumulation in hepatocytes in such disease, we examined whether ethanol exposure induced the transferrin receptor expression and increased the cellular iron uptake. METHODS: Rat primary hepatocytes were isolated and cultured in the presence of 20 micromol/liter of iron and 25 mmol/liter of ethanol. RESULTS: Ethanol exposure to the hepatocytes demonstrated an ~2-fold increase in transferrin receptor expression for 24 hr, shown by Western blot analysis and S-methionine metabolic labeling, 19% increase in Fe-transferrin uptake by hepatocytes, and 20% increase in activity of iron regulatory protein examined by band shift assay. CONCLUSION: Ethanol exposure induced the transferrin receptor expression, partially through the activation of iron regulatory protein, and increased the transferrin-bound iron uptake in rat hepatocyte cultures. The induction of transferrin receptor by ethanol might be one of the mechanisms of iron accumulation in the hepatocytes in alcoholic liver disease.

Animals↗
PubMed1986

Transferrin variants in sheep: separation and characterization by polyacrylamide gel electrophoresis and isoelectric focusing.

Isoelectric focusing with carrier ampholytes in ultrathin polyacrylamide gels and polyacrylamide gel electrophoresis in a discontinuous buffer system were used for the separation of sheep transferrin variants. For identification of the different iron-binding sites of transferrin a stepwise urea gradient, different degrees of iron saturation and double one-dimensional electrophoresis were used. Isoelectric focusing results in an increased resolution of the Fe0-transferrin, Fe1-transferrin and Fe2-transferrin region. At the level of Fe0-transferrin and Fe1-transferrin the variants I, A, G, B, C, D, M, E, Q, P can be identified. The method is especially suitable for genetic studies. For screening purposes up to 108 samples can be separated within one run in an ultrathin gel.

Animals↗
PubMed1985

The iron-chelating agent picolinic acid enhances transferrin receptors expression in human erythroleukaemic cell lines.

Picolinic acid, a metal chelating molecule, was administered to human erythroleukaemic cell lines (K 562 and HEL) that were grown in serum-containing media. Picolinic acid inhibited both iron uptake and cell growth. Furthermore, picolinic acid was shown to markedly decrease the level of ferritin in the cells. In spite of the inhibition of cell growth, picolinic acid induced a marked increase in the transferrin-binding capacity of the cells. This phenomenon was due to a two-five-fold enhancement of the rate of transferrin receptor biosynthesis. Other iron-chelating compounds, capable of reducing the level of intracellular iron, also elicited a marked enhancement of the transferrin-binding capacity of the cells. However, the addition of iron, as ferric ammonium citrate, in the culture medium elicited a marked increase in the level of ferritin and a strong decrease in the transferrin-binding capacity of the cells. On the basis of these data we propose that a feed-back mechanism is involved in the regulation of transferrin receptors: when the cells accumulate iron they decrease the number of transferrin receptors in order to prevent further accumulation of iron; when no or low iron is available to the cells, the number of transferrin receptors markedly increases as a compensatory mechanism.

Cell Line↗
PubMed1994

Transferrin receptors in the normal human hippocampus and in Alzheimer's disease.

Several lines of evidence suggest that aluminium may play a role in the pathogenesis of Alzheimer's disease (AD). The iron transport protein transferrin is the major transport protein for aluminium, and aluminium gains access to cells by means of a specific cell surface transferrin receptor. We have assessed the distribution of transferrin receptors in the normal and AD hippocampal formation using [3H]-transferrin ([3H]-Tf) binding and tritium film autoradiography, in order to assess the role of the transferrin receptor in AD. In normal brain, [3H]-Tf binding was highest in the pyramidal cell layers with CA2 > dentate gyrus granule cell layer > or = CA1 > CA3 > or = CA4 > subiculum > parahippocampal gyrus. In AD, significant reductions in [3H]-Tf binding were found in CA1, CA2 and CA4 pyramidal cell layers. The reduced [3H]-Tf binding in AD may, however, be due to poor pre-mortem agonal states which correlated with reduced [3H]-Tf binding. The discrepancy between the distribution of transferrin receptors in the hippocampus and those areas which are prone to the formation of senile plaques and neurofibrillary tangles suggests that if transferrin-mediated uptake of aluminium in AD/SDAT is significant in the pathogenesis of this disorder, it is not the only determinant of Alzheimer-type neuropathology.

Aged↗
PubMed1984

Transferrin is required for early tooth morphogenesis.

The role of circulating molecules during early tooth morphogenesis was studied in organ cultures of mouse embryonic molar-tooth germs. Special attention was focused on the effect of transferrin and insulin, which are necessary for the growth of most cells in culture. The requirement of serum factors for tooth morphogenesis was shown to diminish as the developmental stage advances from the bud stage in day-13 embryos to the cap stage at day 15. The day-15 teeth underwent morphogenesis and cell differentiation in unsupplemented basal culture medium, but the addition of transferrin (50 micrograms/ml) was necessary for the morphogenesis of day-14 tooth germs. We demonstrated, by using transferrin-depleted serum, that transferrin is also necessary for the morphogenesis of day-13 tooth germs. However, some still-unidentified serum components are also required for the morphogenesis of the bud-stage day-13 teeth. These factors apparently do not include insulin, since it was shown to inhibit tooth development. Analysis of the DNA content of tooth germs cultured in various culture media showed that the ability of transferrin to support tooth morphogenesis correlated with a stimulation of growth. The results support our earlier suggestions that transferrin functions as a fetal growth factor. The availability of the transferrin-containing chemically defined medium facilitates studies on the roles of other growth factors during tooth development.

Animals↗
PubMed1983

Intracellular forms of transferrin oligosaccharide chains in rat liver.

Glycosylation of transferrin was investigated in vivo by using antibody monospecific for rat serum transferrin. Pulse-chase experiments indicated that, after intravenous injection of [35S]methionine, labeled transferrin appeared in the rough and smooth microsomes and Golgi subfractions in rapid succession in 10 min and that an additional 10 min was required for it to be secreted. Most of the intracellular transferrin (95%) immunoprecipitated from the total microsome fraction was sensitive to endo-beta-N-acetylglucosaminidase H (endo H), whereas serum transferrin was completely resistant to it. Further fractionation of the total microsomes has revealed that the intracellular transferrin immunoprecipitated from the rough and smooth microsomes and GF3 are all endo-H-sensitive and most of the endo-H-sensitive oligosaccharides were eluted at the position corresponding to Man8GlcNAc on high-resolution Bio-Gel chromatography. This finding suggests that the major form of intracellular transferrin oligosaccharide in the course of intracellular transport from the endoplasmic reticulum to the Golgi apparatus is Man8GlcNAc2. Endo-H-resistant forms were first detected in the GF2 but more in GF1, most of which were sensitive to neuraminidase. Since the heavy Golgi subfraction contains mainly cis-Golgi elements, such as cisternae, and the light subfraction mainly trans-Golgi elements, such as secretory granules, it is strongly suggested that the processing of these large mannosyloligosaccharide chains and the subsequent addition of terminal sugars to them are performed successively in the trans-Golgi region just before secretion.

Animals↗
PubMed1986

Subcellular localization of transferrin protein and iron in the perfused rat liver. Effect of Triton WR 1339, digitonin and temperature.

The subcellular localization of 3H-labelled 59Fe-loaded transferrin accumulated by the liver has been studied by means of cell fractionation techniques. More than 96% of the 59Fe present in the liver of rats perfused with 59Fe-labelled transferrin is recovered in the parenchymal cells. Rat livers were perfused with 10 micrograms/ml 3H-labelled 59Fe-saturated transferrin, homogenized separated in nuclear (N), mitochondrial (M), light mitochondrial (L), microsomal (P) and supernatant (S) fractions; M, L and P fractions were further analysed by isopycnic centrifugation in sucrose gradients. 3H label distributes essentially around densities of 1.13-1.14 g/ml overlapping to a large extent with the distribution of galactosyltransferase, the marker enzyme of the Golgi complex. However, after treatment with low concentrations of digitonin the 3H label dissociates from galactosyltransferase and is shifted to higher densities, suggesting an association of transferrin with cholesterol-rich endocytic vesicles which could derive from the plasma membrane. 59Fe is mostly found in the supernatant fraction largely in the form of ferritin, as indicated by its reaction with antiferritin antibodies. In the mitochondrial fraction the density distribution of 59Fe suggests an association with lysosomes and/or mitochondria. In contrast to the lysosomal enzyme cathepsin B, the density distribution of 59Fe was only slightly affected by pretreatment of the rats with Triton WR 1339, suggesting its association with the mitochondria. At 15 degrees C, 59Fe and 3H labels are recovered together in low-density endocytic vesicles. On the basis of our results we suggest that, at low extracellular transferrin concentration, iron uptake by the liver involves endocytosis of the transferrin protein. The complex is interiorized in low-density acidic vesicles where iron is released. The iron passes into the cytosol, where it is incorporated into ferritin and into the mitochondria. The iron-depleted transferrin molecule would then be returned to the extracellular medium during the recycling of the plasma membrane.

Animals↗
PubMed1997

Regulation of expression of ferritin H-chain and transferrin receptor by protoporphyrin IX.

The effect of protoporphyrin IX (hemin without iron) on the expression of transferrin receptor and ferritin was investigated in Friend leukemia cells. Cells treated with protoporphyrin IX exhibit enhanced transferrin-receptor expression and markedly reduced ferritin synthesis. Stimulation of transferrin-receptor expression is observed at both the mRNA and protein level. The effect on ferritin synthesis is mediated by translational inhibition of the mRNA, which, in contrast, is transcriptionally stimulated by protoporphyrin IX treatment. The regulation of transferrin receptor and ferritin in response to iron perturbations has been studied extensively and is mediated by the binding of iron-regulatory proteins (IRP) to the iron-responsive elements (IRE) present in the 3' and 5' untranslated regions of the transferrin-receptor and ferritin mRNA, respectively. To elucidate the molecular mechanisms underlying the effects of protoporphyrin IX on ferritin and transferrin-receptor expression, the role of the IRE sequence was investigated both in vivo by transfection experiments, with a construct containing the coding region for the chloramphenicol acetyltransferase (CAT) reporter gene under the translational control of the ferritin IRE, and in vitro by RNA band-shift assays. Whereas, examination of IRP binding to the IRE by in vitro assays suggests an apparent inactivation of IRP by protoporphyrin IX treatment, CAT assays indicate that protoporphyrin IX is able to induce in vivo a translational inhibition similar to that obtained by treatment with the iron chelator Desferal. This observation raises the possibility of different effects on the IRP activity exerted by porphyrin treatment in intact tissue-culture cells and in vitro. We conclude that translation of ferritin mRNA and degradation of transferrin-receptor mRNA are inhibited in intact tissue-culture cells by protoporphyrin IX through a mechanism similar to that exerted by iron chelation, thus involving depletion of the intracellular iron pool. These results can improve the understanding of the regulation of ferritin gene expression in some pathological conditions associated with disturbed heme synthesis.

Animals↗
PubMed1998

Immunohistochemical localization of transferrin in the pre- and postnatal bovine brain.

The distribution of transferrin in brains from fetuses (age-range: 1-2 to 8-9 months of gestational age), calves, subadult (between 1 day and 9 months old) and adult cattle (> 12 months old) were examined by immunohistochemistry. In both pre- and postnatal brains transferrin was predominantly found in oligodendrocytes. Furthermore, transferrin immunostaining was present in single to few neurons, within the lumina of vessels, in endothelial cells, in epithelial cells of the choroid plexus and in ependymal cells. A caudo-rostral progress in the appearance of transferrin-positive cells was found. In fetuses, transferrin-positive mature oligodendrocytes and neurons were not detected before 3-4 months of gestational age. Findings in different brain areas of older fetuses suggest an association between the increase of transferrin-positive oligodendrocytes and the process of myelination. In brains from calves and sub-adult cattle a continuous decrease of transferrin-immunoreactive oligodendrocytes and neurons was noted.

Aging↗
PubMed1991

Expression of transferrin mRNA in the CNS of normal and jimpy mice.

Both the iron mobilization protein transferrin and iron itself are found predominantly in oligodendrocytes in the brain and consequently have been hypothesized to have a role in myelination. This study is designed to begin to understand the mechanism(s) that control the expression of transferrin at the gene level in the nervous system using a hypomyelinating murine mutant (jimpy mouse). With this animal model it is possible to determine if transferrin gene expression in the nervous system is dependent on the presence of a mature oligodendrocytic population. The results demonstrate that normally expression of the transferrin gene increases from postnatal day 5 to 22-25 and then levels off in the adult. In the jimpy mouse, the relative amount of transferrin gene expression is less than that of littermate controls at 5 days of age. Furthermore, transferrin gene expression does not increase with age beyond the level observed at postnatal day 5 in the jimpy mouse. It is concluded from this study that the majority of the transferrin mRNA in the mouse brain is expressed by and/or requires the presence of a mature oligodendrocytic population.

Animals↗
PubMed1992

Iron uptake from transferrin and asialotransferrin by hepatocytes from chronically alcohol-fed rats.

Chronic alcohol intake is often associated with alterations to iron homeostasis and an increase in the serum levels of carbohydrate-deficient transferrin. As the liver is a major iron storage site and also synthesizes transferrin, the normal serum iron transport protein, the aim of this study was to test the hypothesis that these disturbances in iron homeostasis were caused by altered hepatocyte iron uptake from the abnormal transferrin. To achieve this, we have investigated iron uptake from both transferrin and asialotransferrin by hepatocytes from male Sprague-Dawley rats fed the De Carli and Lieber alcohol diet. Iron uptake from transferrin by hepatocytes from alcoholic rats was less than 60% that of control values, and in the presence of 50 mM ethanol decreased still further to 35% of the uptake by the corresponding control cells. Iron uptake from rat asialotransferrin was reduced in both groups when compared to that observed from normal transferrin; 13% by control cells and 39% by hepatocytes from alcohol-fed rats. Alcohol, however, had no further effect on asialotransferrin uptake by either hepatocytes from alcohol-fed rats, or their pair-fed controls. Transferrin binding to hepatocytes was also influenced by the alcohol diet. Although there was no difference in binding at 37 degrees C, cells from alcohol-fed rats bound 85% of this total at 4 degrees C, compared to 44% by control hepatocytes. Similar values were also obtained for hepatocyte binding of asialotransferrin; alcohol feeding resulted in an increase in binding at 4 degrees C to 73% from 58% with control cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1993

Utilization of transferrin-bound iron by Listeria monocytogenes.

It has been demonstrated that under iron-restricted conditions, Listeria monocytogenes can utilize iron-loaded transferrin (Tf) from a range of species as its sole source of iron for growth. Human transferrin conjugated to horseradish-peroxidase (HRP-Tf) bound directly to whole cells of L. monocytogenes. This binding was blocked by apotransferrin indicating that the receptor can bind transferrin in either the iron-bound or iron-free form. Transferrin-binding was not host specific because both bovine and equine transferrin inhibited the binding of HRP-conjugated human transferrin. SDS-PAGE and Western blotting of bacterial surface extracts revealed the presence of a transferrin-binding protein of approximately 126 kDa.

Animals↗
PubMed1982

Transferrin endocytosis in reticulocytes: an electron microscope study using colloidal gold.

The endocytosis of transferrin by rabbit reticulocytes was investigated by electron microscopy using transferrin labelled with colloidal gold. This complex was shown to bind and donate its iron to the cells in a manner comparable to native iron-transferrin. After incubation at 37 degrees C approximately 70% of the transferrin-gold particles were located within endocytotic vesicles. Treatment of the cells with pronase, EDTA, metabolic inhibitors and heating to 46 degrees C inhibited the endocytosis. The uptake of colloidal gold complexes of albumin and concanavalin A were compared with that of transferrin. Little endocytosis of these proteins was observed. It is concluded that colloidal gold is a suitable label for the investigation of transferrin endocytosis and that the endocytosis is specific for transferrin and sensitive to the action of reagents which damage membrane receptors, alter membrane function or impair cell metabolism.

Albumins↗