scholarly journals PTC1 Is Required for Vacuole Inheritance and Promotes the Association of the Myosin-V Vacuole-specific Receptor Complex

2009 ◽  
Vol 20 (5) ◽  
pp. 1312-1323 ◽  
Author(s):  
Yui Jin ◽  
P. Taylor Eves ◽  
Fusheng Tang ◽  
Lois S. Weisman
Keyword(s):  
Protein Phosphatase ◽  
Adaptor Proteins ◽  
Specific Receptor ◽  
Myosin V ◽  
Steady State Levels ◽  
Specific Receptors ◽  
Vacuole Inheritance ◽  
Ash1 Mrna ◽  
Cellular Components ◽  
Cortical Endoplasmic Reticulum

Organelle inheritance occurs during cell division. In Saccharomyces cerevisiae, inheritance of the vacuole, and the distribution of mitochondria and cortical endoplasmic reticulum are regulated by Ptc1p, a type 2C protein phosphatase. Here we show that PTC1/VAC10 controls the distribution of additional cargoes moved by a myosin-V motor. These include peroxisomes, secretory vesicles, cargoes of Myo2p, and ASH1 mRNA, a cargo of Myo4p. We find that Ptc1p is required for the proper distribution of both Myo2p and Myo4p. Surprisingly, PTC1 is also required to maintain the steady-state levels of organelle-specific receptors, including Vac17p, Inp2p, and Mmr1p, which attach Myo2p to the vacuole, peroxisomes, and mitochondria, respectively. Furthermore, Vac17p fused to the cargo-binding domain of Myo2p suppressed the vacuole inheritance defect in ptc1Δ cells. These findings suggest that PTC1 promotes the association of myosin-V with its organelle-specific adaptor proteins. Moreover, these observations suggest that despite the existence of organelle-specific receptors, there is a higher order regulation that coordinates the movement of diverse cellular components.

scholarly journals Identification of an organelle-specific myosin V receptor

2003 ◽  
Vol 160 (6) ◽  
pp. 887-897 ◽  
Author(s):  
Kuniko Ishikawa ◽  
Natalie L. Catlett ◽  
Jennifer L. Novak ◽  
Fusheng Tang ◽  
Johnathan J. Nau ◽  
...  
Keyword(s):  
Secretory Vesicle ◽  
Single Amino Acid ◽  
Single Type ◽  
Specific Receptor ◽  
Myosin V ◽  
Class V ◽  
Vacuole Membrane ◽  
Specific Receptors ◽  
Vacuole Inheritance ◽  
Novel Protein

Class V myosins are widely distributed among diverse organisms and move cargo along actin filaments. Some myosin Vs move multiple types of cargo, where the timing of movement and the destinations of selected cargoes are unique. Here, we report the discovery of an organelle-specific myosin V receptor. Vac17p, a novel protein, is a component of the vacuole-specific receptor for Myo2p, a Saccharomyces cerevisiae myosin V. Vac17p interacts with the Myo2p cargo-binding domain, but not with vacuole inheritance-defective myo2 mutants that have single amino acid changes within this region. Moreover, a region of the Myo2p tail required specifically for secretory vesicle transport is neither required for vacuole inheritance nor for Vac17p–Myo2p interactions. Vac17p is localized on the vacuole membrane, and vacuole-associated Myo2p increases in proportion with an increase in Vac17p. Furthermore, Vac17p is not required for movement of other cargo moved by Myo2p. These findings demonstrate that Vac17p is a component of a vacuole-specific receptor for Myo2p. Organelle-specific receptors such as Vac17p provide a mechanism whereby a single type of myosin V can move diverse cargoes to distinct destinations at different times.

scholarly journals Mouse IgG3 binding to macrophage-like cells is prevented by deglycosylation of the antibody or by Accutase treatment of the cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alicja Karabasz ◽  
Monika Bzowska ◽  
Joanna Bereta ◽  
Maria Czarnek ◽  
Maja Sochalska ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Complex Network ◽  
Immune Cells ◽  
Specific Receptor ◽  
Fcγ Receptors ◽  
Specific Receptors ◽  
First Time

AbstractThe binding of mouse IgG3 to Fcγ receptors (FcγR) and the existence of a mouse IgG3-specific receptor have been discussed for 40 years. Recently, integrin beta-1 (ITGB1) was proposed to be a part of an IgG3 receptor involved in the phagocytosis of IgG3-coated pathogens. We investigated the interaction of mouse IgG3 with macrophage-like J774A.1 and P388D1 cells. The existence of an IgG3-specific receptor was verified using flow cytometry and a rosetting assay, in which erythrocytes clustered around the macrophage-like cells coated with an erythrocyte-specific IgG3. Our findings confirmed that receptors binding antigen-free IgG3 are present on J774A.1 and P388D1 cells. We demonstrated for the first time that the removal of N-glycans from IgG3 completely abolished its binding to the cells. Moreover, we discovered that the cells treated with Accutase did not bind IgG3, indicating that IgG3-specific receptors are substrates of this enzyme. The results of antibody-mediated blocking of putative IgG3 receptors suggested that apart from previously proposed ITGB1, FcγRII, FcγRIII, also additional, still unknown, receptor is involved in IgG3 binding. These findings indicate that there is a complex network of glycan-dependent interactions between mouse IgG3 and the surface of effector immune cells.

Evidence That REM Sleep Is Controlled by the Activation of Brain Stem Pedunculopontine Tegmental Kainate Receptor

2002 ◽  
Vol 87 (4) ◽  
pp. 1790-1798 ◽  
Author(s):  
Subimal Datta
Keyword(s):  
Brain Stem ◽  
Rem Sleep ◽  
Kainate Receptors ◽  
Specific Receptor ◽  
Cell Compartment ◽  
Pharmacological Blockade ◽  
Specific Receptors ◽  
Cholinergic Cell ◽  
First Time ◽  
The Brain

Glutamate, the neurotransmitter, enhances rapid-eye-movement (REM) sleep when microinjected into the brain stem pedunculopontine tegmentum (PPT) of the cat and rat. Glutamate and its various receptors are normally present in the PPT cholinergic cell compartment. The aim of this study was to identify which specific receptor(s) in the cholinergic cell compartment of the PPT are involved in glutamate-induced-REM sleep. To identify these glutamate-induced REM-sleep-generating receptor(s) in the PPT cholinergic cell compartment, specific receptors were pharmacologically blocked differentially by localized pretreatment of specific glutamate receptor antagonists; glutamate was then microinjected into the PPT cholinergic cell compartment while quantifying the effects on REM sleep in freely moving chronically instrumented rats. The results demonstrate that when kainate receptors were blocked by pretreatment with a kainate-specific receptor antagonist, microinjection of glutamate was unable to induce REM sleep. Pharmacological blockade of specific N-methyl-d-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors was unable to block glutamate-microinjection-induced-REM sleep. These findings suggest, for the first time, that the activation of kainate receptors within the cholinergic cell compartment of the PPT is an essential portion of the mechanism for the generation of glutamate-induced REM sleep in the rat.

scholarly journals A Point Mutation in the Cargo-Binding Domain of Myosin V Affects Its Interaction with Multiple Cargoes

2005 ◽  
Vol 4 (4) ◽  
pp. 787-798 ◽  
Author(s):  
Natasha Pashkova ◽  
Natalie L. Catlett ◽  
Jennifer L. Novak ◽  
Lois S. Weisman
Keyword(s):  
Point Mutation ◽  
Specific Binding ◽  
Secretory Vesicle ◽  
Specific Protein ◽  
Myosin V ◽  
Specific Proteins ◽  
Tight Association ◽  
Vacuole Inheritance ◽  
Vesicle Movement ◽  
Cargo Binding

ABSTRACT Class V myosins move diverse intracellular cargoes, which attach via interaction of cargo-specific proteins to the myosin V globular tail. The globular tail of the yeast myosin V, Myo2p, contains two structural and functional subdomains. Subdomain I binds to the vacuole-specific protein, Vac17p, while subdomain II likely binds to an as yet unidentified secretory vesicle-specific protein. All functions of Myo2p require the tight association of subdomains I and II, which suggests that binding of a cargo to one subdomain may inhibit cargo-binding to a second subdomain. Thus, two types of mutations are predicted to specifically affect a subset of Myo2p cargoes: first are mutations within a cargo-specific binding region; second are mutations that mimic the inhibited conformation of one of the subdomains. Here we analyze a point mutation in subdomain I, myo2-2(G1248D), which is likely to be this latter type of mutation. myo2-2 has no effect on secretory vesicle movement. The secretory vesicle binding site is in subdomain II. However, myo2-2 is impaired in several Myo2p-related functions. While subdomains I and II of myo2-2p tightly associate, there are measurable differences in the conformation of its globular tail. Based solely on the ability to restore vacuole inheritance, a set of intragenic suppressors of myo2-2 were identified. All suppressor mutations reside in subdomain I. Moreover, subdomain I and II interactions occurred in all suppressors, demonstrating the importance of subdomain I and II association for Myo2p function. Furthermore, 3 of the 10 suppressors globally restored all tested defects in myo2-2. This large proportion of global suppressors strongly suggests that myo2-2(G1248) causes a conformational change in subdomain I that simultaneously affects multiple cargoes.

scholarly journals Different polarisome components play distinct roles in Slt2p-regulated cortical ER inheritance in Saccharomyces cerevisiae

2013 ◽  
Vol 24 (19) ◽  
pp. 3145-3154 ◽  
Author(s):  
Xia Li ◽  
Susan Ferro-Novick ◽  
Peter Novick
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Protein Kinase ◽  
Protein Phosphatase ◽  
Mitogen Activated Protein Kinase ◽  
Common Mechanism ◽  
Late Step ◽  
Mitogen Activated Protein ◽  
Cortical Endoplasmic Reticulum

Ptc1p, a type 2C protein phosphatase, is required for a late step in cortical endoplasmic reticulum (cER) inheritance in Saccharomyces cerevisiae. In ptc1Δ cells, ER tubules migrate from the mother cell and contact the bud tip, yet fail to spread around the bud cortex. This defect results from the failure to inactivate a bud tip–associated pool of the cell wall integrity mitogen-activated protein kinase, Slt2p. Here we report that the polarisome complex affects cER inheritance through its effects on Slt2p, with different components playing distinct roles: Spa2p and Pea2p are required for Slt2p retention at the bud tip, whereas Bni1p, Bud6p, and Sph1p affect the level of Slt2p activation. Depolymerization of actin relieves the ptc1Δ cER inheritance defect, suggesting that in this mutant the ER becomes trapped on the cytoskeleton. Loss of Sec3p also blocks ER inheritance, and, as in ptc1Δ cells, this block is accompanied by activation of Slt2p and is reversed by depolymerization of actin. Our results point to a common mechanism for the regulation of ER inheritance in which Slt2p activity at the bud tip controls the association of the ER with the actin-based cytoskeleton.

scholarly journals p21-Activated Kinases Cla4 and Ste20 Regulate Vacuole Inheritance in Saccharomyces cerevisiae

2009 ◽  
Vol 8 (4) ◽  
pp. 560-572 ◽  
Author(s):  
Clinton R. Bartholomew ◽  
Christopher F. J. Hardy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Daughter Cell ◽  
Dependent Manner ◽  
Myosin V ◽  
M Phase ◽  
Mother And Daughter ◽  
Specific Proteins ◽  
Vacuole Inheritance ◽  
Specific Degradation ◽  
Segregation Structure

ABSTRACT Each time Saccharomyces cerevisiae cells divide they ensure that both the mother and daughter cell inherit a vacuole by actively transporting a portion of the vacuole into the bud. As the mother cell begins budding, a tubular and vesicular segregation structure forms that is transported into the bud by the myosin V motor Myo2, which is bound to the vacuole-specific myosin receptor, Vac17 (41, 59, 70, 79). Upon arriving in the bud the segregation structure is resolved to found the daughter vacuole. The mechanism that regulates segregation structure resolution in a spatially dependent manner is unknown. In addition to resolving the segregation structure, Vac17 is degraded specifically in the bud to provide directionality to vacuole inheritance. It has been proposed that bud-specific degradation of Vac17 is promoted by proteins localized to or activated solely in the bud (77). The p21-activated kinases (PAKs) Cla4 and Ste20 are localized to and activated in the bud. Here we report that Cla4 is localized to the segregation structure just prior to segregation structure resolution, and cells lacking PAK function fail to resolve the segregation structure. Overexpression of either Cla4 or Ste20 inhibited vacuole inheritance and this inhibition was suppressed by the expression of nondegradable VAC17. Finally, PAK activity was required for Vac17 degradation in late M phase and CLA4 overexpression promoted Vac17 degradation. We propose that Cla4 and Ste20 are bud-specific proteins that play roles in both segregation structure resolution and the degradation of Vac17.

scholarly journals Steady-State Levels of Phosphorylated Mitogen-Activated Protein Kinase Kinase 1/2 Determined by Mortalin/HSPA9 and Protein Phosphatase 1 Alpha in KRAS and BRAF Tumor Cells

2017 ◽  
Vol 37 (18) ◽  
Author(s):  
Pui-Kei Wu ◽  
Seung-Keun Hong ◽  
Jong-In Park
Keyword(s):  
Steady State ◽  
Tumor Cells ◽  
Protein Phosphatase ◽  
Mitogen Activated Protein Kinase ◽  
Binding Assays ◽  
Mitogen Activated Protein ◽  
Binding Cavity ◽  
Steady State Levels ◽  
Erk Activity

ABSTRACT Although deregulation of MEK/extracellular signal-regulated kinase (ERK) activity is a key feature in cancer, high-magnitude MEK/ERK activity can paradoxically induce growth inhibition. Therefore, additional mechanisms may exist to modulate MEK/ERK activity in favor of tumor cell proliferation. We previously reported that mortalin/HSPA9 can facilitate proliferation of certain KRAS and BRAF tumor cells by modulating MEK/ERK activity. In this study, we demonstrated that mortalin can regulate MEK/ERK activity via protein phosphatase 1α (PP1α). We found that PP1α inhibition increases steady-state levels of phosphorylated MEK1/2 in various tumor cells expressing B-RafV600E or K-RasG12C/D. Intriguingly, coimmunoprecipitation and in vitro binding assays revealed that mortalin facilitates PP1α-mediated MEK1/2 dephosphorylation by promoting PP1α-MEK1/2 interaction in an ATP-sensitive manner. The region spanning Val482 to Glu491 in the substrate-binding cavity and the substrate lid of mortalin were necessary for these physical interactions, which is consistent with conventional heat shock protein 70 (HSP70)-client interaction mechanisms. Nevertheless, mortalin depletion did not affect cellular PP1α levels or its regulatory phosphorylation, suggesting a nonconventional role for mortalin in promoting PP1α-MEK1/2 interaction. Of note, PP1α was upregulated in human melanoma and pancreatic cancer biopsy specimens in correlation with mortalin upregulation. PP1α may therefore have a role in tumorigenesis in concert with mortalin, which affects MEK/ERK activity in tumor cells.

scholarly journals Intracellular distribution of haem after uptake by different receptors. Haem-haemopexin and haem-asialo-haemopexin

1985 ◽  
Vol 231 (3) ◽  
pp. 663-669 ◽  
Author(s):  
A Smith
Keyword(s):  
Plasma Membranes ◽  
Colloidal Silica ◽  
Metabolic Fate ◽  
Specific Receptor ◽  
Binding Studies ◽  
Specific Receptors ◽  
Haem Proteins ◽  
Haem Iron

How the interaction of haemopexin with two different receptors affects its subsequent metabolism and ‘intracellular’ haem transport was examined by using mesohaem-haemopexin and mesohaem-asialo-haemopexin. The physical properties of the two haem proteins, including their absorption and c.d. spectra, are similar. Binding studies in vitro showed that haem-asialo-haemopexin interacts with both the haemopexin-specific and galactose-specific receptors on liver plasma membranes, but that haem-haemopexin interacts only with the haemopexin receptor. In vivo haem-asialo-haemopexin rapidly interacts with the liver via the galactose-specific receptor, since the protein is extensively catabolized and uptake is blocked by asialofetuin. Haem iron from haem-asialo-haemopexin is not accumulated in the liver to the same extent as from intact haem-haemopexin, and the native sialylated protein is not proteolysed. Moreover, after fractionation of homogenized liver by using colloidal-silica gradients, liver-associated haem-haemopexin and haem-asialo-haemopexin produced distinctly different patterns for both protein and ligand, consistent with their uptake by two distinct receptors. These results demonstrate that the interaction of haemopexin with different receptors influences its subsequent metabolic fate and that haem iron from haem-haemopexin is efficiently conserved only if it enters the liver cell via the specific haemopexin receptor.

scholarly journals Full length RTN3 regulates turnover of tubular endoplasmic reticulum via selective autophagy

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Paolo Grumati ◽  
Giulio Morozzi ◽  
Soraya Hölper ◽  
Muriel Mari ◽  
Marie-Lena IE Harwardt ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Biological Activity ◽  
Mammalian Cells ◽  
The Other ◽  
Unique Function ◽  
Specific Receptor ◽  
Selective Autophagy ◽  
Specific Receptors ◽  
Autophagy Pathway ◽  
Tubular Endoplasmic Reticulum

The turnover of endoplasmic reticulum (ER) ensures the correct biological activity of its distinct domains. In mammalian cells, the ER is degraded via a selective autophagy pathway (ER-phagy), mediated by two specific receptors: FAM134B, responsible for the turnover of ER sheets and SEC62 that regulates ER recovery following stress. Here, we identified reticulon 3 (RTN3) as a specific receptor for the degradation of ER tubules. Oligomerization of the long isoform of RTN3 is sufficient to trigger fragmentation of ER tubules. The long N-terminal region of RTN3 contains several newly identified LC3-interacting regions (LIR). Binding to LC3s/GABARAPs is essential for the fragmentation of ER tubules and their delivery to lysosomes. RTN3-mediated ER-phagy requires conventional autophagy components, but is independent of FAM134B. None of the other reticulon family members have the ability to induce fragmentation of ER tubules during starvation. Therefore, we assign a unique function to RTN3 during autophagy.

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