Visualizing signalling by phosphoinositide 3-kinase pathway lipids

2004 ◽  
Vol 32 (2) ◽  
pp. 336-337 ◽  
Author(s):  
G.D. Prestwich
Keyword(s):  
Enzyme Activity ◽  
Protein Interactions ◽  
Phosphoinositide Metabolism ◽  
University Of Utah ◽  
Phosphodiester Hydrolysis ◽  
Phosphoinositide 3 Kinase ◽  
Lipid Protein Interactions ◽  
The University ◽  
Hydroxy Groups

Cells signal through lipids produced by phospholipid and phosphoinositide metabolism that involves three enzymic processes: (i) ester and phosphodiester hydrolysis by phospholipases; (ii) monophosphate hydrolysis by phosphatases; and (iii) phosphorylation of hydroxy groups by kinases. Unregulated enzyme activity correlates with specific pathologies, which are specific targets for therapeutic intervention. Three categories of reagents developed at the University of Utah and at Echelon Biosciences permit monitoring of in vitro enzyme activity and spatiotemporal changes in intracellular lipid concentrations, and identification of lipid–protein interactions.

The Origin of the Eukaryotic Cell Based on Conservation of Existing Interfaces

2006 ◽  
Vol 12 (4) ◽  
pp. 513-523 ◽  
Author(s):  
Albert D. G. de Roos
Keyword(s):  
Plasma Membrane ◽  
Protein Interactions ◽  
Self Assembly ◽  
Evolutionary Model ◽  
Lipid Vesicles ◽  
Eukaryotic Cell ◽  
The Self ◽  
Lipid Protein Interactions

Current theories about the origin of the eukaryotic cell all assume that during evolution a prokaryotic cell acquired a nucleus. Here, it is shown that a scenario in which the nucleus acquired a plasma membrane is inherently less complex because existing interfaces remain intact during evolution. Using this scenario, the evolution to the first eukaryotic cell can be modeled in three steps, based on the self-assembly of cellular membranes by lipid-protein interactions. First, the inclusion of chromosomes in a nuclear membrane is mediated by interactions between laminar proteins and lipid vesicles. Second, the formation of a primitive endoplasmic reticulum, or exomembrane, is induced by the expression of intrinsic membrane proteins. Third, a plasma membrane is formed by fusion of exomembrane vesicles on the cytoskeletal protein scaffold. All three self-assembly processes occur both in vivo and in vitro. This new model provides a gradual Darwinistic evolutionary model of the origins of the eukaryotic cell and suggests an inherent ability of an ancestral, primitive genome to induce its own inclusion in a membrane.

scholarly journals The Membrane Proximal Domain of TRPV1 and TRPV2 Channels Mediates Protein–Protein Interactions and Lipid Binding In Vitro

2019 ◽  
Vol 20 (3) ◽  
pp. 682 ◽  
Author(s):  
Pau Doñate-Macián ◽  
Elena Álvarez-Marimon ◽  
Francesc Sepulcre ◽  
José Vázquez-Ibar ◽  
Alex Perálvarez-Marín
Keyword(s):  
Protein Interactions ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Lipid Binding ◽  
Transient Receptor Potential Channels ◽  
Trpv Channels ◽  
Potential Channels ◽  
Transient Receptor ◽  
Lipid Protein Interactions

Constitutive or regulated membrane protein trafficking is a key cell biology process. Transient receptor potential channels are somatosensory proteins in charge of detecting several physical and chemical stimuli, thus requiring fine vesicular trafficking. The membrane proximal or pre-S1 domain (MPD) is a highly conserved domain in transient receptor potential channels from the vanilloid (TRPV) subfamily. MPD shows traits corresponding to protein-protein and lipid-protein interactions, and protein regulatory regions. We have expressed MPD of TRPV1 and TRPV2 as green fluorescente protein (GFP)-fusion proteins to perform an in vitro biochemical and biophysical characterization. Pull-down experiments indicate that MPD recognizes and binds Soluble N-ethylmaleimide-sensitive factor Attachment Protein Receptors (SNARE). Synchrotron radiation scattering experiments show that this domain does not self-oligomerize. MPD interacts with phosphatidic acid (PA), a metabolite of the phospholipase D (PLD) pathway, in a specific manner as shown by lipid strips and Trp fluorescence quenching experiments. We show for the first time, to the best of our knowledge, the binding to PA of an N-terminus domain in TRPV channels. The presence of a PA binding domain in TRPV channels argues for putative PLD regulation. Findings in this study open new perspectives to understand the regulated and constitutive trafficking of TRPV channels exerted by protein-protein and lipid-protein interactions.

scholarly journals MFN2 Influences Amyotrophic Lateral Sclerosis Pathology

2021 ◽  
Author(s):  
Kristi Russell ◽  
Jonathan M. Downie ◽  
Summer Gibson ◽  
Patty Figueroa ◽  
Cody J Steely ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Membrane Potential ◽  
Sequence Data ◽  
Mitochondrial Morphology ◽  
University Of Utah ◽  
Morphological Defects ◽  
The University ◽  
Lateral Sclerosis

Objective: To better understand the pathology of amyotrophic lateral sclerosis, we used sequence data from patients seen at the University of Utah to identify novel disease-associated loci. We utilized both in vitro and in vivo studies to determine the biological effect of patient mutations in MFN2. Methods: Sequence data for a total of 140 patients were run through VAAST and Phevor to determine genes that were more burdened with rare, nonsynonymous variants compared to control longevity cohort. Variants identified in MFN2 were expressed in Mfn2 knockout cells to determine if mutant MFN2 could rescue mitochondrial morphology defects. We identified additional rare, nonsynonymous variants in MFN2 in ALSdb that were expressed in knockout mouse embryonic fibroblasts (MEFs). Membrane potential was measured to quantify mitochondrial health upon mutant MFN2 expression. mfn2 knockout zebrafish were used to examine movement compared to wildtype and protein aggregation in brain. Results: MFN2 mutations identified in ALS patients from our University of Utah cohort and ALSdb were defective in rescuing morphological defects in Mfn2 knockout MEFs. Selected mutants showed decreased membrane potential compared to wildtype MFN2 expression. Zebrafish heterozygous and homozygous for loss of mfn2 showed increased TDP-43 levels in their hindbrain and cerebellum. Conclusion: In total, 21 rare, deleterious mutations in MFN2 were tested in Mfn2 knockout MEFs. Mutant MFN2 expression was not able to rescue the knockout phenotype, though at differing degrees of severity. Decreased membrane potential also argues for inhibited mitochondrial function. Increased TDP-43 levels in mutant zebrafish illustrates MFN2's function in ALS pathology. MFN2 variants influence ALS pathology and highlight the importance of mitochondria in neurodegeneration.

Summary of the University of Utah in vitro fertilization program

1984 ◽  
Vol 1 (1) ◽  
pp. 80-82 ◽  
Author(s):  
Kirtly P. Jones ◽  
William R. Keye ◽  
A. Marsh Poulson ◽  
Richard J. Worley
Keyword(s):  
In Vitro Fertilization ◽  
Fertilization Program ◽  
Vitro Fertilization ◽  
University Of Utah ◽  
The University

scholarly journals The Role of Membranes and Lipid-Protein Interactions in the Mg-Branch of Tetrapyrrole Biosynthesis

2021 ◽  
Vol 12 ◽  
Author(s):  
Katalin Solymosi ◽  
Beata Mysliwa-Kurdziel
Keyword(s):  
Protein Interactions ◽  
Photophysical Properties ◽  
Spectroscopic Properties ◽  
Prolamellar Body ◽  
Tetrapyrrole Biosynthesis ◽  
Whole Plant ◽  
Lipid Protein Interactions ◽  
Envelope Membranes

Chlorophyll (Chl) is essential for photosynthesis and needs to be produced throughout the whole plant life, especially under changing light intensity and stress conditions which may result in the destruction and elimination of these pigments. All steps of the Mg-branch of tetrapyrrole biosynthesis leading to Chl formation are carried out by enzymes associated with plastid membranes. Still the significance of these protein-membrane and protein-lipid interactions in Chl synthesis and chloroplast differentiation are not very well-understood. In this review, we provide an overview on Chl biosynthesis in angiosperms with emphasis on its association with membranes and lipids. Moreover, the last steps of the pathway including the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), the biosynthesis of the isoprenoid phytyl moiety and the esterification of Chlide are also summarized. The unique biochemical and photophysical properties of the light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR) enzyme catalyzing Pchlide photoreduction and located to peculiar tubuloreticular prolamellar body (PLB) membranes of light-deprived tissues of angiosperms and to envelope membranes, as well as to thylakoids (especially grana margins) are also reviewed. Data about the factors influencing tubuloreticular membrane formation within cells, the spectroscopic properties and the in vitro reconstitution of the native LPOR enzyme complexes are also critically discussed.

scholarly journals Reversible binding and rapid diffusion of proteins in complex with inositol lipids serves to coordinate free movement with spatial information

2009 ◽  
Vol 184 (2) ◽  
pp. 297-308 ◽  
Author(s):  
Gerald R.V. Hammond ◽  
Yirong Sim ◽  
Leon Lagnado ◽  
Robin F. Irvine
Keyword(s):  
Protein Interactions ◽  
Spatial Information ◽  
Effector Proteins ◽  
Protein Protein Interactions ◽  
Reversible Binding ◽  
Head Groups ◽  
Lipid Protein Interactions ◽  
And Diffusion ◽  
Similar Affinity

Polyphosphoinositol lipids convey spatial information partly by their interactions with cellular proteins within defined domains. However, these interactions are prevented when the lipids' head groups are masked by the recruitment of cytosolic effector proteins, whereas these effectors must also have sufficient mobility to maximize functional interactions. To investigate quantitatively how these conflicting functional needs are optimized, we used different fluorescence recovery after photobleaching techniques to investigate inositol lipid–effector protein kinetics in terms of the real-time dissociation from, and diffusion within, the plasma membrane. We find that the protein–lipid complexes retain a relatively rapid (∼0.1–1 µm2/s) diffusion coefficient in the membrane, likely dominated by protein–protein interactions, but the limited time scale (seconds) of these complexes, dictated principally by lipid–protein interactions, limits their range of action to a few microns. Moreover, our data reveal that GAP1IP4BP, a protein that binds PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in vitro with similar affinity, is able to “read” PtdIns(3,4,5)P3 signals in terms of an elongated residence time at the membrane.

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