Abstract:
:Absorption of dietary fat in the small intestine involves epithelial exposure to potentially harmful molecules such as bile salts and free fatty acids. We used organ culture of porcine jejunal explants incubated with a pre-digested mixture of fat (plant oil), bile and pancreatin to mimick the physiological process of dietary fat absorption, and short exposures to the fat mixture caused fat droplet accumulation within villus enterocytes. Lucifer yellow (LY), a fluorescent membrane-impermeable polar tracer was included to monitor epithelial integrity. Both in controls and during fat absorption LY penetrated the epithelium and accumulated in the basal lamina and the lamina propria. LY was also seen in the paracellular space, whereas villus enterocytes were generally only weakly labeled except for small amounts taken up by apical endocytosis. In the crypts, however, fat absorption induced cell permeabilization with LY accumulating in the cytosol and nucleus. Morphologically, both apical and basolateral membranes appeared intact, indicating that the leakiness was caused by minor lesions in the membrane. Albeit to a lesser extent, bile alone was capable of permeabilizing crypt cells, implying that the surfactant properties of bile salts are involved in the process. In addition to LY, crypt enterocytes also became permeable for albumin, ovalbumin and insulin. In conclusion, during fat absorption the permeability of the gut epithelium is increased mainly in the crypts. A possible explanation is that cell membranes of immature crypt cells, lacking detergent-resistant lipid raft microdomains, are less resistant to the deleterious effects of bile salts and free fatty acids.
journal_name
Mol Membr Bioljournal_title
Molecular membrane biologyauthors
Danielsen EM,Hansen GH,Rasmussen K,Niels-Christiansen LLdoi
10.3109/09687688.2013.780642subject
Has Abstractpub_date
2013-05-01 00:00:00pages
261-72issue
3eissn
0968-7688issn
1464-5203journal_volume
30pub_type
杂志文章abstract::Flavonoids are ubiquitous polyphenolic compounds, found in vascular plants, which are endowed with a large variety of biological effects. Some of these effects have been assumed to result from interactions with the cell plasma membrane. In order to investigate the nature of these interactions a fluorescence study was ...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.1080/096876899294616
更新日期:1999-04-01 00:00:00
abstract::The number of structures of integral membrane proteins from higher eukaryotes is steadily increasing due to a number of innovative protein engineering and crystallization strategies devised over the last few years. However, it is sobering to reflect that these structures represent only a tiny proportion of the total n...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.3109/09687688.2012.703703
更新日期:2013-02-01 00:00:00
abstract::Temperature-composition phase diagrams of binary lipid mixtures under conditions of constant pressure and excess water show that component immiscibility is the rule rather than the exception in these systems. Phase immiscibility is particularly noted in the solid phase but several cases are known where immiscibility i...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687689509038493
更新日期:1995-01-01 00:00:00
abstract::4-Hydroxy-2-nonenal (4-HNE) is a reactive aldehyde and a lipid peroxidation product formed in biological tissues under physiological and pathological conditions. Its concentration increases with oxidative stress and induces deleterious modifications of proteins and membranes. Mitochondrial and cytosolic isoforms of cr...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687688.2015.1023376
更新日期:2015-01-01 00:00:00
abstract::The Amt/Mep/Rh family of integral membrane proteins comprises ammonium transporters of bacteria, archaea and eukarya, as well as the Rhesus proteins found in animals. They play a central role in the uptake of reduced nitrogen for biosynthetic purposes, in energy metabolism, or in renal excretion. Recent structural inf...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.1080/09687680701388423
更新日期:2007-09-01 00:00:00
abstract::Spontaneous membrane adsorption, folding and insertion of the synthetic WALP16 and KALP16 peptides was studied by computer simulations starting from completely extended conformations. The peptides were simulated using an unmodified all-atom force field in combination with an efficient Monte Carlo sampling algorithm. T...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.1080/09687680802020313
更新日期:2008-04-01 00:00:00
abstract::The Signal Recognition Particle (SRP) plays a critical role in the sorting of nascent secretory and membrane proteins. Remarkably, this function has been conserved from bacteria, where SRP delivers proteins to the inner membrane, through to eukaryotes, where SRP is required for targeting of proteins to the endoplasmic...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.1080/09687860400026348
更新日期:2005-01-01 00:00:00
abstract::Calpain, an intracellular calcium-dependent protease, is activated at cell membranes and cleaves cytoskeletal and submembranous proteins. Calpain is inferred to be a calcium-dependent regulator for cytoskeletal reorganization. Calpastatin, an endogenous calpain inhibitor, inhibits not only the proteolytic activity of ...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.3109/09687689609160599
更新日期:1996-10-01 00:00:00
abstract::Glycosyl-phosphatidylinositol (GPI)-anchored proteins are enriched in cholesterol- and sphingolipid-rich lipid rafts within the membrane. Rafts are known to have roles in cellular organization and function, but little is understood about the factors controlling the distribution of proteins in rafts. We have used atomi...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.1080/09687860601127770
更新日期:2007-05-01 00:00:00
abstract::Notch is a vitally important signalling receptor controlling cell fate determination and pattern formation in numerous ways during development of both invertebrate and vertebrate species. An intriguing pathway for the Notch signal has emerged where, after ligand-dependent proteolysis, an intracellular fragment of the ...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.1080/09687680110112929
更新日期:2002-01-01 00:00:00
abstract::Amiodarone (AMI) is a low water-solubility drug, which is very useful in the treatment of severe cardiac disease. Its adverse effects are associated with toxicity in different tissues. Several antioxidants have been shown to reduce, and prevent AMI toxicity. The aim of this work was to develop and characterize Dimyris...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687688.2014.896956
更新日期:2014-03-01 00:00:00
abstract::Evidence was recently reported that the cysteine proteinase inhibitor, cystatin C, is highly expressed by cultured human retinal pigment epithelial (RPE) cells. As a step towards understanding possible functions of this protein associated with the RPE, the localization, targetting and trafficking of cystatin C were in...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.1080/09687680110075101
更新日期:2001-07-01 00:00:00
abstract::Time and distance scales in membranes are discussed in relation to the inference of domain structure from spectroscopic measurements. Each type of spectroscopy has a natural time scale set by the magnitude of the interactions that determine the spectral width. For fluid membranes, the lateral diffusion of the lipid mo...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.3109/09687689509038489
更新日期:1995-01-01 00:00:00
abstract::Membrane proteins are ubiquitous in biology and are key targets for therapeutic development. Despite this, our structural understanding has lagged behind that of their soluble counterparts. This review provides an overview of this important field, focusing in particular on the recent resurgence of electron microscopy ...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.1080/09687688.2016.1221533
更新日期:2016-03-01 00:00:00
abstract::Equilibrative Nucleoside Transporters (SLC29) are a family of proteins that transport nucleosides, nucleobases and nucleoside analogue drugs across cellular membranes. ENT1 is expressed ubiquitously in mammalian tissues and responsible for a significant portion of nucleoside analog drug uptake in humans. Despite the i...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687688.2011.604861
更新日期:2011-09-01 00:00:00
abstract::Glucosyltransferases (Gtrs) and O-acetyltransferase (Oac) are integral membrane proteins embedded within the cytoplasmic membrane of Shigella flexneri. Gtrs and Oac are responsible for unidirectional host serotype conversion by altering the epitopic properties of the bacterial surface lipopolysaccharide (LPS) O-antige...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687680903552250
更新日期:2010-04-01 00:00:00
abstract::The effect of cholesterol and lanosterol on the formation of structures in the gel/subgel phase of 1,2-dipalmitoylphosphatidylcholine was investigated using freeze-fracture electron microscopy and X-ray diffraction. Mixtures with up to 25 mol% sterol were analysed after annealing for between several days and some mont...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687689709048181
更新日期:1997-10-01 00:00:00
abstract::The cyanelles of the glaucocystophyte alga Cyanophora paradoxa resemble endosymbiotic cyanobacteria in morphology, pigmentation and, especially, in the presence of a peptidoglycan wall situated between the inner and outer envelope membranes. However, it is now clear that cyanelles in fact are primitive plastids. Phylo...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.1080/09687860500041411
更新日期:2005-01-01 00:00:00
abstract::Site-directed mutagenesis and site-directed fluorescence spectroscopy demonstrate that Cys148 interacts hydrophobically with the galactosyl moiety of substrates of the lactose permease of Escherichia coli. By taking advantage of the finding that labelling of single-Cys148 permease with the thiol-specific fluorophore 2...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687689809027513
更新日期:1998-01-01 00:00:00
abstract::The mitochondrial ADP/ATP carrier imports ADP from the cytosol into the mitochondrial matrix for its conversion to ATP by ATP synthase and exports ATP out of the mitochondrion to replenish the eukaryotic cell with chemical energy. Here the substrate specificity of the human mitochondrial ADP/ATP carrier AAC1 was deter...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687688.2012.745175
更新日期:2013-03-01 00:00:00
abstract::Significant progress has been made in membrane protein engineering over the last 5 years, based largely on the re-design of existing scaffolds. Engineering techniques that have been employed include direct genetic engineering, both covalent and non-covalent modification, unnatural amino acid mutagenesis and total synt...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.1080/09687680410001716853
更新日期:2004-07-01 00:00:00
abstract::Microorganisms that survive in natural environments form organized multicellular communities, biofilms and colonies with specific properties. During stress and nutrient limitation, slow growing and senescent cells in such communities retain vital processes by maintaining plasma membrane integrity and retaining the abi...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.1080/09687680902893130
更新日期:2009-05-01 00:00:00
abstract::Small GTPase Rab36 is homologous to Rab34 with 56% amino acid sequence identity. Rab34 was characterized as a Golgi-associated Rab protein and regulates lysosomal positioning through interaction with RILP; however, the properties and functions of Rab36 have not been investigated. To investigate Rab36, we constructed E...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687680903417470
更新日期:2010-01-01 00:00:00
abstract::Gap junctions are plasma membrane spatial microdomains constructed of assemblies of channel proteins called connexins in vertebrates and innexins in invertebrates. The channels provide direct intercellular communication pathways allowing rapid exchange of ions and metabolites up to approximately 1 kD in size. Approxim...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.1080/09687680210139839
更新日期:2002-04-01 00:00:00
abstract::Solid-state NMR combined with sample deuteration was used to probe the proximity of the low-affinity substrate D-glucose to its binding site within the Escherichia coli sugar transport protein GalP. Samples of E. coli inner membranes with amplified expression of GalP were incubated in D(2)O with D-[(13)C(6)]glucose an...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687688.2012.743193
更新日期:2013-03-01 00:00:00
abstract::The number of Signal Peptidase I (SPasel) molecules per E. coli cell was determined using western blot techniques. Different strains were found to contain approximately 1000 SPasel molecules per cell during exponential growth. Based on the activity of SPasel in vitro it could be estimated that this amount is sufficien...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687689509072437
更新日期:1995-10-01 00:00:00
abstract::This review describes the numerous and innovative methods used to study the structure and function of viral fusion peptides. The systems studied include both intact fusion proteins and synthetic peptides interacting with model membranes. The strategies and methods include dissecting the fusion process into intermediat...
journal_title:Molecular membrane biology
pub_type: 杂志文章,评审
doi:10.3109/09687689709048170
更新日期:1997-07-01 00:00:00
abstract::Palmitoylation is required for the activities of several cancer-associated proteins, making the palmitoyl acyltransferase (PAT) enzymes that catalyze these reactions potential targets for anticancer therapeutics. In this study, we sought to identify and characterize a human PAT with activity toward N-terminally myrist...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687681003616854
更新日期:2010-04-01 00:00:00
abstract::Membrane proteins are intrinsically involved in both human and pathogen physiology, and are the target of 60% of all marketed drugs. During the past decade, advances in the studies of membrane proteins using X-ray crystallography, electron microscopy and NMR-based techniques led to the elucidation of over 250 unique m...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.3109/09687688.2012.710341
更新日期:2013-03-01 00:00:00
abstract::Trypsin activation of Cry4B, a 130-kDa Bacillus thuringiensis (Bt) protein, produces a 65-kDa toxin active against mosquito larvae. The active toxin is made of two protease resistant-products of ca. 45 kDa and ca. 20 kDa. The cloned 21-kDa fragment consisting of the N-terminal region of the toxin was previously shown ...
journal_title:Molecular membrane biology
pub_type: 杂志文章
doi:10.1080/09687680310001625792
更新日期:2004-01-01 00:00:00