Maturation of early endosomes and vesicular traffic to lysosomes in relation to membrane recycling

1995 ◽  
Vol 108 (4) ◽  
pp. 1791-1803 ◽  
Author(s):  
L. Thilo ◽  
E. Stroud ◽  
T. Haylett
Keyword(s):  
Fluid Phase ◽  
Endocytic Pathway ◽  
Second Phase ◽  
Membrane Recycling ◽  
Order Process ◽  
Vesicular Traffic ◽  
First Order ◽  
Early Endosomes ◽  
Kinetics Of ◽  
Late Stages

The controversy whether endocytic processing occurs by organellar maturation or by vesicular traffic has not been resolved. It is also not clear whether maturation continues to the stage of lysosomes, to what extent it involves a decrease in organellar fusogenicity, and how it relates to membrane recycling. Maturation and vesicular traffic imply distinct kinetics for the intermingling of endocytic markers after sequential endocytic uptake. We have studied the kinetics of intermingling of fluid-phase markers (fluorescein-labelled dextran and horseradish peroxidase) and cell surface-derived membrane (labelled by galactosylation) in organelles at early and late stages of the endocytic pathway in macrophage-like P388D1 cells. Intermingling declined by sigmoid kinetics, indicating that endosomes matured within about 3 minutes to become non-fusogenic towards early endosomes. During maturation about 60% of internalized membrane was recycled with T1/2 approximately 2 minutes. Whereas matured endosomes were non-fusogenic towards early endosomes and towards each other, a second phase of intermingling was observed upon delivery to lysosomes. This intermingling occurred by a first-order process (T1/2 approximately 4 minutes), concurrent with recycling of the remaining 40% of internalized membrane marker. These kinetic observations suggest a model for endocytic processing which reconciles maturation of early endosomes with the known function of carrier vesicles: Endocytic carrier vesicles do not bud off from permanent early endosomes as proposed for vesicular traffic, but are derived, together with recycling vesicles, from the maturation of early endosomes which are consumed by this process; these carrier vesicles subsequently mediate delivery to lysosomes by vesicular traffic during which the remaining surface-derived membrane is recycled.

scholarly journals A Myosin I Is Involved in Membrane Recycling from Early Endosomes

2000 ◽  
Vol 150 (5) ◽  
pp. 1013-1026 ◽  
Author(s):  
Eva M. Neuhaus ◽  
Thierry Soldati
Keyword(s):  
Plasma Membrane ◽  
Fluid Phase ◽  
Surface Proteins ◽  
Endocytic Pathway ◽  
Membrane Recycling ◽  
Myosin I ◽  
Early Endosomes ◽  
Butanedione Monoxime ◽  
Microscopy Method ◽  
Membrane Components

Geometry-based mechanisms have been proposed to account for the sorting of membranes and fluid phase in the endocytic pathway, yet little is known about the involvement of the actin–myosin cytoskeleton. Here, we demonstrate that Dictyostelium discoideum myosin IB functions in the recycling of plasma membrane components from endosomes back to the cell surface. Cells lacking MyoB (myoA−/B−, and myoB− cells) and wild-type cells treated with the myosin inhibitor butanedione monoxime accumulated a plasma membrane marker and biotinylated surface proteins on intracellular endocytic vacuoles. An assay based on reversible biotinylation of plasma membrane proteins demonstrated that recycling of membrane components is severely impaired in myoA/B null cells. In addition, MyoB was specifically found on magnetically purified early pinosomes. Using a rapid-freezing cryoelectron microscopy method, we observed an increased number of small vesicles tethered to relatively early endocytic vacuoles in myoA−/B− cells, but not to later endosomes and lysosomes. This accumulation of vesicles suggests that the defects in membrane recycling result from a disordered morphology of the sorting compartment.

scholarly journals REGENERATION OF VISUAL PURPLE IN SOLUTION

1939 ◽  
Vol 23 (1) ◽  
pp. 21-39 ◽  
Author(s):  
Aurin M. Chase ◽  
Emil L. Smith
Keyword(s):  
Order Process ◽  
First Order ◽  
Color Changes ◽  
Violet Light ◽  
Frog Retina ◽  
Significant Difference ◽  
Kinetics Of ◽  
Photosensitive Substance ◽  
Subsequent Regeneration

1. Measurements of visual purple regeneration in solution have been made by a procedure which minimized distortion of the results by other color changes so that density changes caused by the regenerating substance alone are obtained. 2. Bleaching a visual purple solution with blue and violet light causes a greater subsequent regeneration than does an equivalent bleaching with light which lacks blue and violet. This is due to a photosensitive substance which has a gradually increasing effective absorption toward the shorter wavelengths. It is uncertain whether this substance is a product of visual purple bleaching or is present in the solution before illumination. 3. The regeneration of visual purple measured at 560 mµ is maximal at about pH 6.7 and decreases markedly at more acid and more alkaline pH's. 4. The absorption spectrum of the regenerating material shows only a concentration change during the course of regeneration, but has a higher absorption at the shorter wavelengths than has visual purple before illumination. 5. Visual purple extractions made at various temperatures show no significant difference in per cent of regeneration. 6. The kinetics of regeneration is usually that of a first order process. Successive regenerations in the same solution have the same velocity constant but form smaller total amounts of regenerated substance. 7. In vivo, the frog retina shows no additional oxygen consumption while visual purple is regenerating.

Spectrochemical Behavior of Carcinogenic Polycyclic Aromatic Hydrocarbons in Biological Systems. Part II: A Theoretical Rate Model for BaP Metabolism in Living Cells

1996 ◽  
Vol 50 (11) ◽  
pp. 1352-1359 ◽  
Author(s):  
Ping Chiang ◽  
Kuang-Pang Li ◽  
Tong-Ming Hseu
Keyword(s):  
Rate Constant ◽  
Living Cells ◽  
Rate Model ◽  
Number Density ◽  
Order Process ◽  
Irreversible Reaction ◽  
First Order ◽  
Metabolism Rate ◽  
Polycyclic Aromatic ◽  
Kinetics Of

An idealized model for the kinetics of benzo[ a]pyrene (BaP) metabolism is established. As observed from experimental results, the BaP transfer from microcrystals to the cell membrane is definitely a first-order process. The rate constant of this process is signified as k1. We describe the surface–midplane exchange as reversible and use rate constants k2 and k3 to describe the inward and outward diffusions, respectively. The metabolism is identified as an irreversible reaction with a rate constant k4. If k2 and k3 are assumed to be fast and not rate determining, the effect of the metabolism rate, k4, on the number density of BaP in the midplane of the microsomal membrane, m3, can be estimated. If the metabolism rate is faster than or comparable to the distribution rates, k2 and k3, the BaP concentration in the membrane midplane, m3, will quickly be dissipated. But if k4 is extremely small, m3 will reach a plateau. Under conditions when k2 and k3 also play significant roles in determining the overall rate, more complicated patterns of m3 are expected.

scholarly journals Recycling pathways of glucosylceramide in BHK cells: distinct involvement of early and late endosomes

1992 ◽  
Vol 103 (4) ◽  
pp. 1139-1152
Author(s):  
J.W. Kok ◽  
K. Hoekstra ◽  
S. Eskelinen ◽  
D. Hoekstra
Keyword(s):  
Plasma Membrane ◽  
Intracellular Ph ◽  
Brefeldin A ◽  
Fluid Phase ◽  
Endocytic Pathway ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Recycling Pathway ◽  
Golgi Network ◽  
Extensive Involvement

Recycling pathways of the sphingolipid glucosylceramide were studied by employing a fluorescent analog of glucosylceramide, 6(-)[N-(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]hexanoylglucosyl sphingosine (C6-NBD-glucosylceramide). Direct recycling of the glycolipid from early endosomes to the plasma membrane occurs, as could be shown after treating the cells with the microtubule-disrupting agent nocodazole, which causes inhibition of the glycolipid's trafficking from peripheral early endosomes to centrally located late endosomes. When the microtubuli are intact, at least part of the glucosylceramide is transported from early to late endosomes together with ricin. Interestingly, also N-(lissamine rhodamine B sulfonyl)phosphatidylethanolamine (N-Rh-PE), a membrane marker of the fluid-phase endocytic pathway, is transported to this endosomal compartment. However, in contrast to both ricin and N-Rh-PE, the glucosylceramide can escape from this organelle and recycle to the plasma membrane. Monensin and brefeldin A have little effect on this recycling pathway, which would exclude extensive involvement of early Golgi compartments in recycling. Hence, the small fraction of the glycolipid that colocalizes with transferrin (Tf) in the Golgi area might directly recycle via the trans-Golgi network. When the intracellular pH was lowered to 5.5, recycling was drastically reduced, in accordance with the impeding effect of low intracellular pH on vesicular transport during endocytosis and in the biosynthetic pathway. Our results thus demonstrate the existence of at least two recycling pathways for glucosylceramide and indicate the relevance of early endosomes in recycling of both proteins and lipids.

scholarly journals The combination of carbon monoxide–haem with apoperoxidase

1969 ◽  
Vol 114 (4) ◽  
pp. 719-724 ◽  
Author(s):  
Charles Phelps ◽  
Eraldo Antonini
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Rate Constant ◽  
Binding Sites ◽  
Order Process ◽  
First Order ◽  
Effects Of Ph ◽  
Kinetics Of

1. Static titrations reveal an exact stoicheiometry between various haem derivatives and apoperoxidase prepared from one isoenzyme of the horseradish enzyme. 2. Carbon monoxide–protohaem reacts rapidly with apoperoxidase and the kinetics can be accounted for by a mechanism already applied to the reaction of carbon monoxide–haem derivatives with apomyoglobin and apohaemoglobin. 3. According to this mechanism a complex is formed first whose combination and dissociation velocity constants are 5×108m−1sec.−1 and 103sec.−1 at pH9·1 and 20°. The complex is converted into carbon monoxide–haemoprotein in a first-order process with a rate constant of 235sec.−1 for peroxidase and 364sec.−1 for myoglobin at pH9·1 and 20°. 4. The effects of pH and temperature were examined. The activation energy for the process of complex-isomerization is about 13kcal./mole. 5. The similarity in the kinetics of the reactions of carbon monoxide–haem with apoperoxidase and with apomyoglobin suggests structural similarities at the haem-binding sites of the two proteins.

Reaction Kinetics of Thrombin Activity in Decalcified Plasma and Blood

1969 ◽  
Vol 21 (03) ◽  
pp. 580-593
Author(s):  
L. A Pálos ◽  
G Sas ◽  
A Csurgay
Keyword(s):  
Reaction Kinetics ◽  
Mathematical Expression ◽  
Second Phase ◽  
Thrombin Time ◽  
First Order ◽  
Functional Relationships ◽  
First Order Kinetics ◽  
Set Up ◽  
Kinetics Of

SummaryThe reaction kinetics of the second phase of blood clotting (conversion of fibrinogen to fibrin) has been studied in euglobulin and thrombin-antithrombin systems. It was intended to set up relationships that would make mathematical expression of the processes possible and which would, moreover, help in detecting dynamic and functional relationships characteristic of the mechanism involved in coagulation.The experiments have yielded the following results:1. In the euglobulin solution containing no antithrombin the fibrinogen-thrombin reaction can be characterized with a constant deviation from the first order kinetics.2. The process of thrombin inactivation is a reaction of first order in the initial phase.3. The two basic processes (clotting by thrombin in euglobulin solution, inactivation of thrombin in defibrinated plasma) make it possible to predetermine the thrombin time of citrated plasma. Theoretical and actual clotting times were in good agreement.4. The thrombin time of plasma can be computed even if thrombin is not introduced to the system at one stride but gradually, a manner of administration which is a better imitation of what happening in vivo. 5. In connection with the computation of the “thrombin time” of citrated blood, we determined experimentally (and expressed by means of a function) the modification produced by the corpuscular elements of the blood in the reaction between fibrinogen and thrombin under atraumatic conditions.

scholarly journals Endocytosis in filter-grown Madin-Darby canine kidney cells.

1989 ◽  
Vol 109 (6) ◽  
pp. 3243-3258 ◽  
Author(s):  
M Bomsel ◽  
K Prydz ◽  
R G Parton ◽  
J Gruenberg ◽  
K Simons
Keyword(s):  
Cell Layer ◽  
Mdck Cells ◽  
Fluid Phase ◽  
Perinuclear Region ◽  
Apical Side ◽  
Early Endosomes ◽  
Basolateral Side ◽  
Endocytic Compartments ◽  
Kinetics Of ◽  
Endocytic Pathways

In this paper, we have characterized the apical and basolateral endocytic pathways of epithelial MDCK cells grown on filters. The three-dimensional organization of the endocytic compartments was analyzed by confocal microscopy after internalization of a fluorescent fluid-phase marker from either side of the cell layer. After 5 min of internalization, distinct sets of apical and basolateral early endosomes were observed lining the plasma membrane domain from which internalization had occurred. At later time points, the apical and the basolateral endocytic pathways were shown to converge in the perinuclear region. Mixing of two different fluorescent markers could be detected after their simultaneous internalization from opposite sides of the cell layer. The extent of the meeting was quantitated by measuring the amount of complex formed intracellularly between avidin internalized from the apical side and biotinylated horseradish peroxidase (HRP) from the basolateral side. After 15 min, 14% of the avidin marker was complexed with the biotinylated HRP and this value increased to 50% during a subsequent chase of 60 min in avidin-free medium. We also determined the kinetics of fluid internalization, recycling, transcytosis, and intracellular retention using HRP as a marker. Fluid was internalized with the same rates from either surface domain (1.2 x 10(-4) microns 3/min per microns 2 of surface area). However, significant differences were observed for each pathway in the amounts and kinetics of marker recycled and transcytosed. The content of apical early endosomes was primarily recycled and transcytosed (45% along Bach route after 1 h internalization), whereas delivery to late endocytic compartments was favored from the basolateral early endosome (77% after 1 h). Our results demonstrate that early apical and basolateral endosomes are functionally and topologically distinct, but that the endocytic pathways converge at later stages in the perinuclear region of the cell.

Kinetics of Chain Scission of Natural Rubber

1989 ◽  
Vol 62 (5) ◽  
pp. 779-787
Author(s):  
M. S. Sambhi
Keyword(s):  
Oxidative Degradation ◽  
Oxidation Mechanism ◽  
Chain Scission ◽  
Bimolecular Reaction ◽  
Zero Order ◽  
Order Kinetic ◽  
Peroxy Radicals ◽  
Order Process ◽  
First Order ◽  
Kinetics Of

Abstract The first-order and zero-order kinetic models of chain scission, based on random chain scission processes, are critically examined. It is likely that for many practical situations, the first-order chain scission kinetics can be represented by pseudozero-order kinetic types of equations. The kinetic results indicate that chain scission of NR occurs either by a pseudofirst-order or a pseudozero-order process. The pseudozero-order chain scission kinetics of NR are in consonance with the result that chain scission involves the bimolecular reaction of peroxy radicals in the termination step of the oxidation mechanism. However, this does not preclude unambiguously other chain scission reactions. The chain scission activation energy of NR is determined with the use of expressions derived for the oxidative degradation of NR as measured in terms of Wallace plasticities.

scholarly journals APPL endosomes are not obligatory endocytic intermediates but act as stable cargo-sorting compartments

2015 ◽  
Vol 211 (1) ◽  
pp. 123-144 ◽  
Author(s):  
Inna Kalaidzidis ◽  
Marta Miaczynska ◽  
Marta Brewińska-Olchowik ◽  
Anna Hupalowska ◽  
Charles Ferguson ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mathematical Models ◽  
Endocytic Pathway ◽  
Distinct Population ◽  
Primary Mechanism ◽  
Cargo Transport ◽  
Early Endosomes ◽  
Kinetics Of ◽  
Vesicular Compartment ◽  
Over Time

Endocytosis allows cargo to enter a series of specialized endosomal compartments, beginning with early endosomes harboring Rab5 and its effector EEA1. There are, however, additional structures labeled by the Rab5 effector APPL1 whose role in endocytic transport remains unclear. It has been proposed that APPL1 vesicles are transport intermediates that convert into EEA1 endosomes. Here, we tested this model by analyzing the ultrastructural morphology, kinetics of cargo transport, and stability of the APPL1 compartment over time. We found that APPL1 resides on a tubulo-vesicular compartment that is capable of sorting cargo for recycling or degradation and that displays long lifetimes, all features typical of early endosomes. Fitting mathematical models to experimental data rules out maturation of APPL1 vesicles into EEA1 endosomes as a primary mechanism for cargo transport. Our data suggest instead that APPL1 endosomes represent a distinct population of Rab5-positive sorting endosomes, thus providing important insights into the compartmental organization of the early endocytic pathway.

scholarly journals A mutation in glyceraldehyde 3-phosphate dehydrogenase alters endocytosis in CHO cells.

1995 ◽  
Vol 130 (5) ◽  
pp. 1093-1104 ◽  
Author(s):  
A R Robbins ◽  
R D Ward ◽  
C Oliver
Keyword(s):  
Fluid Phase ◽  
Glycolytic Enzyme ◽  
Two Dimensions ◽  
Cdna Clones ◽  
Wild Type ◽  
Stable Transfectants ◽  
Single Nucleotide Change ◽  
Early Endosomes ◽  
Endocytic Compartments ◽  
Kinetics Of

The CHO cell mutant FD 1.3.25 exhibits both increased accumulation and altered distribution of endocytosed fluid phase tracers. Neither the rate of tracer internalization nor the kinetics of recycling from early endosomes was affected, but exocytosis from late endocytic compartments appeared to be decreased in the mutant. Endocytosed tracer moved more rapidly to the cell poles in FD1.3.25 than in wild type cells. An abundant 36-kD polypeptide was found associated with taxol-polymerized microtubules in preparations from wild type and mutant; in the former but not the latter this polypeptide could be dissociated by incubation of the microtubules in ATP or high salt. The 36-kD polypeptide co-electrophoresed in two dimensions with the monomer of the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Analysis of cDNA clones showed that the mutant is heterozygous for this enzyme, with approximately 25% of the GAPDH RNA containing a single nucleotide change resulting in substitution of Ser for Pro234, a residue that is conserved throughout evolution. Stable transfectants of wild type cells expressing the mutant monomer at approximately 15% of the total enzyme exhibited the various changes in endocytosis observed in FD1.3.25.

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