The Manganese Cation Disrupts Membrane Dynamics along the Secretory Pathway

2000 ◽  
Vol 259 (1) ◽  
pp. 167-179 ◽  
Author(s):  
Mhairi C. Towler ◽  
Alan R. Prescott ◽  
John James ◽  
John M. Lucocq ◽  
Sreenivasan Ponnambalam
Keyword(s):  
Secretory Pathway ◽  
Membrane Dynamics ◽  
Manganese Cation

scholarly journals Distinct Roles for the Yeast Phosphatidylinositol 4-Kinases, Stt4p and Pik1p, in Secretion, Cell Growth, and Organelle Membrane Dynamics

2000 ◽  
Vol 11 (8) ◽  
pp. 2673-2689 ◽  
Author(s):  
Anjon Audhya ◽  
Michelangelo Foti ◽  
Scott D. Emr
Keyword(s):  
Cell Growth ◽  
Membrane Trafficking ◽  
Secretory Pathway ◽  
Membrane Dynamics ◽  
Small Gtpase ◽  
Effector Proteins ◽  
Restrictive Temperature ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cytoskeleton Organization ◽  
Yeast Viability

The yeast Saccharomyces cerevisiae possesses two genes that encode phosphatidylinositol (PtdIns) 4-kinases,STT4 and PIK1. Both gene products phosphorylate PtdIns at the D-4 position of the inositol ring to generate PtdIns(4)P, which plays an essential role in yeast viability because deletion of either STT4 orPIK1 is lethal. Furthermore, although both enzymes have the same biochemical activity, increased expression of either kinase cannot compensate for the loss of the other, suggesting that these kinases regulate distinct intracellular functions, each of which is required for yeast cell growth. By the construction of temperature-conditional single and double mutants, we have found that Stt4p activity is required for the maintenance of vacuole morphology, cell wall integrity, and actin cytoskeleton organization. In contrast, Pik1p is essential for normal secretion, Golgi and vacuole membrane dynamics, and endocytosis. Strikingly,pik1tscells exhibit a rapid defect in secretion of Golgi-modified secretory pathway cargos, Hsp150p and invertase, whereas stt4tscells exhibit no detectable secretory defects. Both single mutants reduce PtdIns(4)P by ∼50%; however,stt4ts/pik1tsdouble mutant cells produce more than 10-fold less PtdIns(4)P as well as PtdIns(4,5)P2. The aberrant Golgi morphology found in pik1tsmutants is strikingly similar to that found in cells lacking the function of Arf1p, a small GTPase that is known to regulate multiple membrane trafficking events throughout the cell. Consistent with this observation, arf1 mutants exhibit reduced PtdIns(4)P levels. In contrast, diminished levels of PtdIns(4)P observed in stt4tscells at restrictive temperature result in a dramatic change in vacuole size compared with pik1tscells and persistent actin delocalization. Based on these results, we propose that Stt4p and Pik1p act as the major, if not the only, PtdIns 4-kinases in yeast and produce distinct pools of PtdIns(4)P and PtdIns(4,5)P2that act on different intracellular membranes to recruit or activate as yet uncharacterized effector proteins.

Membrane Dynamics in the Early Secretory Pathway

2007 ◽  
Vol 26 (4) ◽  
pp. 199-225 ◽  
Author(s):  
David G. Robinson ◽  
Marie-Carmen Herranz ◽  
Julia Bubeck ◽  
Rainer Pepperkok ◽  
Christophe Ritzenthaler
Keyword(s):  
Secretory Pathway ◽  
Membrane Dynamics ◽  
Early Secretory Pathway

Defects in early secretory pathway transport machinery components and neurodevelopmental disorders

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Bor Luen Tang
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Secretory Pathway ◽  
Underlying Disease ◽  
Membrane Dynamics ◽  
Coat Proteins ◽  
Disease Manifestation ◽  
Vesicular Traffic ◽  
Early Secretory Pathway ◽  
Genes Encoding

Abstract The early secretory pathway, provisionally comprising of vesicular traffic between the endoplasmic reticulum (ER) and the Golgi apparatus, occurs constitutively in mammalian cells. Critical for a constant supply of secretory and plasma membrane (PM) materials, the pathway is presumably essential for general cellular function and survival. Neurons exhibit a high intensity in membrane dynamics and protein/lipid trafficking, with differential and polarized trafficking towards the somatodendritic and axonal PM domains. Mutations in genes encoding early secretory pathway membrane trafficking machinery components are known to result in neurodevelopmental or neurological disorders with disease manifestation in early life. Here, such rare disorders associated with autosomal recessive mutations in coat proteins, membrane tethering complexes and membrane fusion machineries responsible for trafficking in the early secretory pathway are summarily discussed. These mutations affected genes encoding subunits of coat protein complex I and II, subunits of transport protein particle (TRAPP) complexes, members of the YIP1 domain family (YIPF) and a SNAP receptor (SNARE) family member. Why the ubiquitously present and constitutively acting early secretory pathway machinery components could specifically affect neurodevelopment is addressed, with the plausible underlying disease etiologies and neuropathological mechanisms resulting from these mutations explored.

scholarly journals Quantitative mass spectrometry reveals a role for the GTPase Rho1p in actin organization on the peroxisome membrane

2004 ◽  
Vol 167 (6) ◽  
pp. 1099-1112 ◽  
Author(s):  
Marcello Marelli ◽  
Jennifer J. Smith ◽  
Sunhee Jung ◽  
Eugene Yi ◽  
Alexey I. Nesvizhskii ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Large Scale ◽  
Secretory Pathway ◽  
Subcellular Fractionation ◽  
Membrane Dynamics ◽  
Small Gtpase ◽  
Quantitative Mass Spectrometry ◽  
Actin Organization ◽  
Associated Proteins ◽  
Peroxisome Membrane

We have combined classical subcellular fractionation with large-scale quantitative mass spectrometry to identify proteins that enrich specifically with peroxisomes of Saccharomyces cerevisiae. In two complementary experiments, isotope-coded affinity tags and tandem mass spectrometry were used to quantify the relative enrichment of proteins during the purification of peroxisomes. Mathematical modeling of the data from 306 quantified proteins led to a prioritized list of 70 candidates whose enrichment scores indicated a high likelihood of them being peroxisomal. Among these proteins, eight novel peroxisome-associated proteins were identified. The top novel peroxisomal candidate was the small GTPase Rho1p. Although Rho1p has been shown to be tethered to membranes of the secretory pathway, we show that it is specifically recruited to peroxisomes upon their induction in a process dependent on its interaction with the peroxisome membrane protein Pex25p. Rho1p regulates the assembly state of actin on the peroxisome membrane, thereby controlling peroxisome membrane dynamics and biogenesis.

Application of FRAP and digitized fluorescence microscopy to problems in cell membrane dynamics

1988 ◽  
Vol 46 ◽  
pp. 118-119
Author(s):  
K. Jacobson ◽  
A. Ishihara ◽  
B. Holifield ◽  
F. Zhang
Keyword(s):  
Fluorescence Microscopy ◽  
Cell Biology ◽  
Extended Period ◽  
Dynamic Structure ◽  
Living Cells ◽  
Membrane Dynamics ◽  
Molecular Cell Biology ◽  
Image Averaging ◽  
Single Living Cells ◽  
Single Living

Our laboratory is concerned with understanding the dynamic structure of the plasma membrane with particular reference to the movement of membrane constituents during cell locomotion. In addition to the standard tools of molecular cell biology, we employ both fluorescence recovery after photo- bleaching (FRAP) and digitized fluorescence microscopy (DFM) to investigate individual cells. FRAP allows the measurement of translational mobility of membrane and cytoplasmic molecules in small regions of single, living cells. DFM is really a new form of light microscopy in that the distribution of individual classes of ions, molecules, and macromolecules can be followed in single, living cells. By employing fluorescent antibodies to defined antigens or fluorescent analogs of cellular constituents as well as ultrasensitive, electronic image detectors and video image averaging to improve signal to noise, fluorescent images of living cells can be acquired over an extended period without significant fading and loss of cell viability.

Coaction of Electrostatic and Hydrophobic Interactions: Dynamic Constraints on Disordered TrkA Juxtamembrane Domain

2019 ◽  
Author(s):  
Zichen Wang ◽  
Huaxun Fan ◽  
Xiao Hu ◽  
John Khamo ◽  
Jiajie Diao ◽  
...  
Keyword(s):  
Single Molecule ◽  
Protein Function ◽  
Hydrophobic Interactions ◽  
Transmembrane Helix ◽  
Point Mutations ◽  
Salt Bridge ◽  
Receptor Activation ◽  
Membrane Dynamics ◽  
Juxtamembrane Domain ◽  
Joint Work

<p>The receptor tyrosine kinase family transmits signals into cell via a single transmembrane helix and a flexible juxtamembrane domain (JMD). Membrane dynamics makes it challenging to study the structural mechanism of receptor activation experimentally. In this study, we employ all-atom molecular dynamics with Highly Mobile Membrane-Mimetic to capture membrane interactions with the JMD of tropomyosin receptor kinase A (TrkA). We find that PIP<sub>2 </sub>lipids engage in lasting binding to multiple basic residues and compete with salt bridge within the peptide. We discover three residues insertion into the membrane, and perturb it through computationally designed point mutations. Single-molecule experiments indicate the contribution from hydrophobic insertion is comparable to electrostatic binding, and in-cell experiments show that enhanced TrkA-JMD insertion promotes receptor ubiquitination. Our joint work points to a scenario where basic and hydrophobic residues on disordered domains interact with lipid headgroups and tails, respectively, to restrain flexibility and potentially modulate protein function.</p>

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