scholarly journals Plasma Membrane Lipids: An Important Binding Site for All Lipoprotein Classes

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 882
Author(s):  
Markus Axmann ◽  
Birgit Plochberger ◽  
Mario Mikula ◽  
Florian Weber ◽  
Witta Monika Strobl ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Binding Site ◽  
Plasma Membranes ◽  
De Novo ◽  
Membrane Lipids ◽  
Density Lipoprotein ◽  
Blood Stream ◽  
Lipoprotein Particles ◽  
Membrane Contact Sites ◽  
Extracellular Transport

Cholesterol is one of the main constituents of plasma membranes; thus, its supply is of utmost importance. This review covers the known mechanisms of cholesterol transfer from circulating lipoprotein particles to the plasma membrane, and vice versa. To achieve homeostasis, the human body utilizes cellular de novo synthesis and extracellular transport particles for supply of cholesterol and other lipids via the blood stream. These lipoprotein particles can be classified according to their density: chylomicrons, very low, low, and high-density lipoprotein (VLDL, LDL, and HDL, respectively). They deliver and receive their lipid loads, most importantly cholesterol, to and from cells by several redundant routes. Defects in one of these pathways (e.g., due to mutations in receptors) usually are not immediately fatal. Several redundant pathways, at least temporarily, compensate for the loss of one or more of them, but the defects trigger systemic diseases, such as atherosclerosis later on. Recently, intracellular membrane–membrane contact sites were shown to be involved in intracellular cholesterol transfer and the plasma membrane itself has been proposed to act as a binding site for lipoprotein-mediated cargo unloading.

scholarly journals Plasma membrane association of Acanthamoeba myosin I.

1989 ◽  
Vol 109 (4) ◽  
pp. 1519-1528 ◽  
Author(s):  
H Miyata ◽  
B Bowers ◽  
E D Korn
Keyword(s):  
Plasma Membrane ◽  
Binding Site ◽  
Heavy Chain ◽  
Membrane Fraction ◽  
Plasma Membranes ◽  
Actin Binding ◽  
Plasma Membrane Fraction ◽  
Myosin I ◽  
Membrane Bound ◽  
Actin Binding Site

Myosin I accounted for approximately 2% of the protein of highly purified plasma membranes, which represents about a tenfold enrichment over its concentration in the total cell homogenate. This localization is consistent with immunofluorescence analysis of cells that shows myosin I at or near the plasma membrane as well as diffusely distributed in the cytoplasm with no apparent association with cytoplasmic organelles or vesicles identifiable at the level of light microscopy. Myosin II was not detected in the purified plasma membrane fraction. Although actin was present in about a tenfold molar excess relative to myosin I, several lines of evidence suggest that the principal linkage of myosin I with the plasma membrane is not through F-actin: (a) KI extracted much more actin than myosin I from the plasma membrane fraction; (b) higher ionic strength was required to solubilize the membrane-bound myosin I than to dissociate a complex of purified myosin I and F-actin; and (c) added purified myosin I bound to KI-extracted plasma membranes in a saturable manner with maximum binding four- to fivefold greater than the actin content and with much greater affinity than for pure F-actin (apparent KD of 30-50 nM vs. 10-40 microM in 0.1 M KCl plus 2 mM MgATP). Thus, neither the MgATP-sensitive actin-binding site in the NH2-terminal end of the myosin I heavy chain nor the MgATP-insensitive actin-binding site in the COOH-terminal end of the heavy chain appeared to be the principal mechanism of binding of myosin I to plasma membranes through F-actin. Furthermore, the MgATP-sensitive actin-binding site of membrane-bound myosin I was still available to bind added F-actin. However, the MgATP-insensitive actin-binding site appeared to be unable to bind added F-actin, suggesting that the membrane-binding site is near enough to this site to block sterically its interaction with actin.

Composition, biophysical properties, and morphometry of plasma membranes in pulmonary interstitial edema

2002 ◽  
Vol 282 (6) ◽  
pp. L1382-L1390 ◽  
Author(s):  
Paola Palestini ◽  
Chiara Calvi ◽  
Elena Conforti ◽  
Laura Botto ◽  
Carla Fenoglio ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Plasma Membranes ◽  
Cell Activation ◽  
Membrane Lipids ◽  
Gradient Centrifugation ◽  
Mechanical Stimuli ◽  
Biophysical Properties ◽  
Interstitial Edema ◽  
Vascular Perfusion

We evaluated the changes in plasma membrane composition, biophysical properties, and morphology of pulmonary endothelial cells in anesthetized rabbits receiving 0.5 ml · kg−1 · min−1 saline infusion for 180 min, causing mild interstitial edema. Plasma membrane fractions were obtained from lung homogenates with gradient centrifugation, allowing a sixfold enrichment in caveolin-1. In edematous lungs, cholesterol content and phospholipidic phosphorus increased by 15 and 40%, respectively. These data correlated with morphometric analysis of lungs fixed in situ by vascular perfusion with 2.5% glutaraldehyde, suggesting a relative increase in surface of luminal to interstitial front of the capillary endothelial cells, due to a convoluted luminal profile. In edematous lungs, the fraction of double-bound fatty acids increased in membrane lipids; moreover, the phosphatidylcholine/phosphatidylethanolamine and the cholesterol/phospholipid ratios decreased. These changes were consistent with the increase in fluorescence anisotropy of plasma membrane, indicating an increase in its fluidity. Data suggest that mechanical stimuli elicited by a modest (∼4%) increase in extravascular water cause marked changes in plasma membranes that may be of relevance in signal transduction and endothelial cell activation.

scholarly journals Cytochemical evidence for the presence of phospholipids in epithelial tight junction strands.

1993 ◽  
Vol 41 (5) ◽  
pp. 649-656 ◽  
Author(s):  
F W Kan
Keyword(s):  
Plasma Membrane ◽  
Tight Junction ◽  
Phospholipase A2 ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Freeze Fracture ◽  
Fracture Face ◽  
Gold Particles ◽  
Pancreatic Cells ◽  
Specific Association

Previous freeze-fracture experiments using either glutaraldehyde-fixed and cryoprotected specimens or unfixed rapid-frozen samples led to the proposal that cylindrical strands of the tight junction (TJ) observed in freeze-fracture preparations are inverted cylindrical micelles made up of membrane lipids and, possibly, membrane proteins. However, no one has yet been able to directly label the structural fibrils of the TJ. To test the hypothesis that TJ strands observed on freeze-fracture preparations are composed at least partially of lipids, we have combined the phospholipase A2-gold and the fracture-label techniques for localization of phospholipids. Phospholipase A2, purified from bee venom, was adsorbed on gold particles and used for specific labeling of its substrate. Phospholipase A2-colloidal gold (PLA2-CG) complex was applied to freeze-fractured preparations of rat exocrine pancreatic cells and testicular Sertoli cells, both of which are known to have extensive TJ complexes on their plasma membranes. Fracture-label replicas of exocrine pancreatic cells revealed specific association of gold particles with TJ fibrils on the protoplasmic fracture-face of the plasma membrane. The majority of these gold particles were observed either directly on the top of the TJ fibrils or adjacent to these cylindrical structures. A high density of PLA2-CG labeling was also observed over the complementary exoplasmic fracture-face of the TJ complex. This intimate association of PLA2-CG labeling with the TJ is particularly evident in the Sertoli cell plasma membrane, where rows of gold particles were observed to be superimposed on parallel arrays of cylindrical strands of the TJ complex. The present findings provide direct cytochemical evidence to support the hypothesis that cylindrical TJ strands observed in freeze-fracture preparations contain phospholipids.

scholarly journals F-actin binds to the cytoplasmic surface of ponticulin, a 17-kD integral glycoprotein from Dictyostelium discoideum plasma membranes.

1987 ◽  
Vol 105 (4) ◽  
pp. 1741-1751 ◽  
Author(s):  
L J Wuestehube ◽  
E J Luna
Keyword(s):  
Plasma Membrane ◽  
Binding Site ◽  
Dictyostelium Discoideum ◽  
Plasma Membranes ◽  
Membrane Binding ◽  
Binding Activity ◽  
Actin Binding ◽  
Actin Binding Protein ◽  
Cytoplasmic Surface ◽  
Actin Binding Site

F-actin affinity chromatography and immunological techniques are used to identify actin-binding proteins in purified Dictyostelium discoideum plasma membranes. A 17-kD integral glycoprotein (gp17) consistently elutes from F-actin columns as the major actin-binding protein under a variety of experimental conditions. The actin-binding activity of gp17 is identical to that of intact plasma membranes: it resists extraction with 0.1 N NaOH, 1 mM dithiothreitol (DTT); it is sensitive to ionic conditions; it is stable over a wide range of pH; and it is eliminated by proteolysis, denaturation with heat, or treatment with DTT and N-ethylmaleimide. gp17 may be responsible for much of the actin-binding activity of plasma membranes since monovalent antibody fragments (Fab) directed primarily against gp17 inhibit actin-membrane binding by 96% in sedimentation assays. In contrast, Fab directed against cell surface determinants inhibit binding by only 0-10%. The actin-binding site of gp17 appears to be located on the cytoplasmic surface of the membrane since Fab against this protein continue to inhibit 96% of actin-membrane binding even after extensive adsorption against cell surfaces. gp17 is abundant in the plasma membrane, constituting 0.4-1.0% of the total membrane protein. A transmembrane orientation of gp17 is suggested since, in addition to the cytoplasmic localization of the actin-binding site, extracellular determinants of gp17 are identified. gp17 is surface-labeled by sulfo-N-hydroxy-succinimido-biotin, a reagent that cannot penetrate the cell membrane. Also, gp17 is glycosylated since it is specifically bound by the lectin, concanavalin A. We propose that gp17 is a major actin-binding protein that is important for connecting the plasma membrane to the underlying microfilament network. Therefore, we have named this protein "ponticulin" from the Latin word, ponticulus, which means small bridge.

scholarly journals Efficient Trafficking of MDR1/P-Glycoprotein to Apical Canalicular Plasma Membranes in HepG2 Cells Requires PKA-RIIα Anchoring and Glucosylceramide

2006 ◽  
Vol 17 (8) ◽  
pp. 3638-3650 ◽  
Author(s):  
Kacper A. Wojtal ◽  
Erik de Vries ◽  
Dick Hoekstra ◽  
Sven C.D. van IJzendoorn
Keyword(s):  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Hepg2 Cells ◽  
Plasma Membranes ◽  
De Novo ◽  
Apical Plasma Membrane ◽  
Apical Surface ◽  
Surface Transport ◽  
P Glycoprotein ◽  
Dpp Iv

In hepatocytes, cAMP/PKA activity stimulates the exocytic insertion of apical proteins and lipids and the biogenesis of bile canalicular plasma membranes. Here, we show that the displacement of PKA-RIIα from the Golgi apparatus severely delays the trafficking of the bile canalicular protein MDR1 (P-glycoprotein), but not that of MRP2 (cMOAT), DPP IV and 5′NT, to newly formed apical surfaces. In addition, the direct trafficking of de novo synthesized glycosphingolipid analogues from the Golgi apparatus to the apical surface is inhibited. Instead, newly synthesized glucosylceramide analogues are rerouted to the basolateral surface via a vesicular pathway, from where they are subsequently endocytosed and delivered to the apical surface via transcytosis. Treatment of HepG2 cells with the glucosylceramide synthase inhibitor PDMP delays the appearance of MDR1, but not MRP2, DPP IV, and 5′NT at newly formed apical surfaces, implicating glucosylceramide synthesis as an important parameter for the efficient Golgi-to-apical surface transport of MDR1. Neither PKA-RIIα displacement nor PDMP inhibited (cAMP-stimulated) apical plasma membrane biogenesis per se, suggesting that other cAMP effectors may play a role in canalicular development. Taken together, our data implicate the involvement of PKA-RIIα anchoring in the efficient direct apical targeting of distinct proteins and glycosphingolipids to newly formed apical plasma membrane domains and suggest that rerouting of Golgi-derived glycosphingolipids may underlie the delayed Golgi-to-apical surface transport of MDR1.

Temperature-induced physical changes in fungal plasma membranes

1980 ◽  
Vol 58 (10) ◽  
pp. 1138-1143 ◽  
Author(s):  
R. W. Miller
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Protein Complexes ◽  
Divalent Cations ◽  
Freeze Fracture ◽  
Ordered Structures ◽  
Membrane Protein Complexes ◽  
Hexagonally Ordered ◽  
Physical Changes

Ordered structures suggesting phase separation of lipids were observed in freeze-fracture replicas of plasma membranes of Fusarium sulphureum after free protoplasts had been fixed at 0 °C. Areas representing up to 50% of the protoplast plasma membrane inner fractured face assumed a lateral, hexagonally ordered structure from which the normally randomly distributed 25-nm membrane protein complexes had been excluded. Intact macroconidia only rarely showed small regions of lateral ordering of this type when fixed at the same, nonlethal temperature.The normal impermeability of the macroconidial plasma membrane to divalent cations such as Ni2+ declined rapidly when the cells were incubated at temperatures 5 °C or more above the physiological growth temperature range of the organism. Admission of divalent cations and death of the cells was associated with an irreversible thermotropic change in the fluidity in the membrane lipids as indicated by lipophilic spin probes.Partitioning spin probe and freeze-fracture techniques were best suited to the observation of thermotropic physical changes in the fungal plasma membrane which were induced at supra- and sub-physiological temperatures, respectively.

Endogenous hyperphosphorylation in plasma membrane from an ascites hepatocarcinoma cell line

1988 ◽  
Vol 66 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Jon G. Church ◽  
Shobha Ghosh ◽  
Basil D. Roufogalis ◽  
Antonio Villalobo
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Cell Line ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Normal Adult ◽  
Plasma Membrane Proteins ◽  
Phosphoprotein Phosphatase ◽  
Membrane Bound

Plasma-membrane-bound kinases of AS-30D ascites from transplantable rat hepatocarcinoma were shown to extensively catalyze the phosphorylation of plasma membrane proteins and membrane lipids, using [γ-32P]ATP or [γ-32P]GTP as a phosphate donor. In contrast, plasma membranes from normal adult rat liver or fast-growing regenerating liver (24 h after partial hepatectomy) produce significantly less activity for protein phosphorylation and little phosphorylation of the lipids. However, neonatal (24 h old) rat liver plasma membrane preparations show levels of phosphorylation of proteins and lipids intermediate between those in the tumor cell line and normal adult plasma membrane preparations. Phosphatidic acid was identified as one of the 32P-labelled lipids in the tumor plasma membrane chloroform–methanol (2:1, v/v) extract. Phosphorylation of protein was not affected by cAMP or cGMP. However, calcium ion (in the presence or absence of calmodulin) significantly modifies the 32P labelling of a series of proteins in normal tissue but has little effect with the neoplastic preparations. Some plasma membrane proteins were capable of nucleotide binding, instead or in addition to being phosphorylated. Finally, the presence of membrane-bound phosphoprotein phosphatase(s) was also demonstrated in all the preparations examined by means of chase experiments with nonlabelled ATP or GTP, and (or) by the use of the phosphoprotein phosphatase inhibitor, orthovanadate.

scholarly journals Lipoprotein particles interact with membranes and transfer their cargo without receptors

2020 ◽  
Author(s):  
Birgit Plochberger ◽  
Taras Sych ◽  
Florian Weber ◽  
Jiri Novacek ◽  
Markus Axmann ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membrane ◽  
Low Density Lipoprotein ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
Blood Stream ◽  
Correlation Spectroscopy ◽  
Lipid Transfer ◽  
Independent Manner ◽  
Lipoprotein Particles

AbstractLipid transfer from lipoprotein particles to cells is essential for lipid homeostasis. High density lipoprotein (HDL) particles are mainly captured by cell-membrane-associated scavenger receptor class B type 1 (SR-B1) from the blood stream while low and very low density lipoprotein (LDL, VLDL) particles are mostly taken up by receptor-mediated endocytosis. However, the role of the target lipid membrane itself in the transfer process has been largely neglected so far. Here, we study how lipoprotein particles (HDL, LDL and VLDL) interact with synthetic lipid bilayers and cell-derived membranes and transfer their cargo subsequently. Employing cryo-electron microscopy, spectral imaging and fluorescence (cross) correlation spectroscopy allowed us to observe integration of all major types of lipoprotein particles into the membrane and delivery of their cargo in a receptor-independent manner. Importantly, biophysical properties of the target cell membranes change upon cargo delivery. The concept of receptor-independent interaction of lipoprotein particles with membranes helps to better understand lipoprotein particle biology and can be exploited for novel treatments of dyslipidemia diseases.

scholarly journals Diffusion and regionalization in membranes of maturing ram spermatozoa.

1984 ◽  
Vol 98 (5) ◽  
pp. 1678-1684 ◽  
Author(s):  
D E Wolf ◽  
J K Voglmayr
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Essential Feature ◽  
Lateral Diffusion ◽  
Mammalian Sperm ◽  
Epididymal Maturation ◽  
Cell Plasma ◽  
Sperm Plasma Membrane ◽  
Membrane Components

An essential feature of the "fluid mosaic model" (Singer, S. J., and G. L. Nicolson , 1972, Science (Wash. DC)., 175:720-731) of the cell plasma membrane is the ability of membrane lipids and proteins to diffuse laterally in the plane of the membrane. Mammalian sperm are capable of overcoming free random diffusion and restricting specific membrane components, both lipid and protein, to defined regions of the sperm's surface. The patterns of these regionalizations evolve with the processes of sperm differentiation: spermatogenesis, epididymal maturation, and capacitation. We have used the technique of fluorescence recovery after photobleaching to measure the diffusion of the lipid analogue 1,1'- dihexadecyl 3,3,3',3'- tetramethylindocarbocyanine perchlorate ( C16dil ) on the different morphological regions of testicular and ejaculated ram spermatozoa. We have found: (a) that the major morphologically distinct regions (head, midpiece, and tail) of the plasma membrane of both testicular and ejaculated spermatozoa are also physically distinct as measured by C16dil diffusibility; (b) that despite regional differences in diffusibility there is exchange of this lipid analogue by lateral diffusion between the major morphological regions of the plasma membrane; and (c) that epididymal maturation results in changes in C16dil diffusibility in the different regions of the sperm plasma membrane. In particular, the plasma membranes of the anterior and posterior heads become physically distinct.

Intracellular trafficking of glycosylphosphatidylinositol (GPI)-anchored proteins and free GPIs in Leishmania mexicana

2002 ◽  
Vol 363 (2) ◽  
pp. 365-375 ◽  
Author(s):  
Julie E. RALTON ◽  
Kylie A. MULLIN ◽  
Malcolm J. McCONVILLE
Keyword(s):  
Plasma Membrane ◽  
Intracellular Trafficking ◽  
Intracellular Transport ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Significant Proportion ◽  
Leishmania Mexicana ◽  
Cytoplasmic Face ◽  
Triton X ◽  
Sphingolipid Biosynthesis

Free glycosylphosphatidylinositols (GPIs) are an important class of membrane lipids in many pathogenic protozoa. In this study, we have investigated the subcellular distribution and intracellular trafficking of an abundant class of free GPIs [termed glycosylinositolphospholipids (GIPLs)] in Leishmania mexicana promastigotes. The intracellular transport of the GIPLs and the major GPI-anchored glycoprotein gp63 was measured by following the incorporation of these molecules into sphingolipid-rich, detergent-resistant membranes (DRMs) in the plasma membrane. In metabolic-labelling experiments, mature GIPLs and gp63 were transported to DRMs in the plasma membrane with a t1/2 of 70 and 40min, respectively. Probably, GIPL transport to the DRMs involves a vesicular mechanism, as transport of both the GIPLs and gp63 was inhibited similarly at 10°C. All GIPL intermediates were quantitatively recovered in Triton X-100-soluble membranes and were largely orientated on the cytoplasmic face of the endoplasmic reticulum, as shown by their sensitivity to exogenous phosphatidylinositol-specific phospho-lipase C. On the contrary, a significant proportion of the mature GIPLs (≈50% of iM4) were accessible to membrane-impermeable probes on the surface of live promastigotes. These results suggest that the GIPLs are flipped across intracellular or plasma membranes during surface transport and that a significant fraction may populate the cytoplasmic leaflet of the plasma membrane. Finally, treatment of L. mexicana promastigotes with myriocin, an inhibitor of sphingolipid biosynthesis, demonstrated that ongoing sphingolipid biosynthesis is not required for the plasma-membrane transport of either gp63 or the GIPLs and that DRMs persist even when cellular levels of the major sphingolipid are depleted by 70%.

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