scholarly journals The N-glycans of lactoferrin: More than just a sweet decoration.

2020 ◽  
Author(s):  
Kristina Zlatina ◽  
Sebastian Peter Galuska
Keyword(s):  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Extracellular Proteins ◽  
Bovine Lactoferrin ◽  
Carrier Protein ◽  
Therapeutic Approaches ◽  
Heterogeneous Effects ◽  
Potential Impact ◽  
Sugar Chains ◽  
Different Origins

Nearly all extracellular proteins undergo posttranslational modification with sugar chains during their transit through the endoplasmic reticulum and the Golgi apparatus. These “sweet” modifications not only influence the activity of its carrier protein, but they themselves often have bioactivity, independent of the carrier function. Lactoferrin belongs to the group of glycoproteins and is modified with several different N-glycans. This review summarizes several studies dealing with the diverse glycosylation patterns of lactoferrin from different origins and the potential impact of these posttranslational modifications on the functionality of lactoferrin. A special emphasis is placed on the differences between human and bovine lactoferrin, since the latter form is often selected for the development of novel therapeutic approaches in humans. For this reason, the potential impact of the bovine-specific glycosylation patterns on the observed heterogeneous effects of lactoferrin in humans is discussed within this review.

Neurofilaments and Paired Helical Filaments

1985 ◽  
Vol 43 ◽  
pp. 740-743
Author(s):  
J. Metuzals
Keyword(s):  
Animal Model ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Giant Axon ◽  
Paired Helical Filaments ◽  
Squid Giant Axon ◽  
In Vitro Experiments ◽  
Thin Sections ◽  
Structural Relationships

It has been demonstrated that the neurofibrillary tangles in biopsies of Alzheimer patients, composed of typical paired helical filaments (PHF), consist also of typical neurofilaments (NF) and 15nm wide filaments. Close structural relationships, and even continuity between NF and PHF, have been observed. In this paper, such relationships are investigated from the standpoint that the PHF are formed through posttranslational modifications of NF. To investigate the validity of the posttranslational modification hypothesis of PHF formation, we have identified in thin sections from frontal lobe biopsies of Alzheimer patients all existing conformations of NF and PHF and ordered these conformations in a hypothetical sequence. However, only experiments with animal model preparations will prove or disprove the validity of the interpretations of static structural observations made on patients. For this purpose, the results of in vitro experiments with the squid giant axon preparations are compared with those obtained from human patients. This approach is essential in discovering etiological factors of Alzheimer's disease and its early diagnosis.

scholarly journals The intracellular dynamic of protein palmitoylation

2010 ◽  
Vol 191 (7) ◽  
pp. 1229-1238 ◽  
Author(s):  
Christine Salaun ◽  
Jennifer Greaves ◽  
Luke H. Chamberlain
Keyword(s):  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Mammalian Cells ◽  
Protein Functionality ◽  
Peripheral Membrane Proteins ◽  
Protein Palmitoylation ◽  
Thioester Bond ◽  
Intracellular Sorting ◽  
Intracellular Dynamic ◽  
Insight Into

S-palmitoylation describes the reversible attachment of fatty acids (predominantly palmitate) onto cysteine residues via a labile thioester bond. This posttranslational modification impacts protein functionality by regulating membrane interactions, intracellular sorting, stability, and membrane micropatterning. Several recent findings have provided a tantalizing insight into the regulation and spatiotemporal dynamics of protein palmitoylation. In mammalian cells, the Golgi has emerged as a possible super-reaction center for the palmitoylation of peripheral membrane proteins, whereas palmitoylation reactions on post-Golgi compartments contribute to the regulation of specific substrates. In addition to palmitoylating and depalmitoylating enzymes, intracellular palmitoylation dynamics may also be controlled through interplay with distinct posttranslational modifications, such as phosphorylation and nitrosylation.

scholarly journals VPTMdb: a viral posttranslational modification database

2020 ◽  
Author(s):  
Yujia Xiang ◽  
Quan Zou ◽  
Lilin Zhao
Keyword(s):  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Drug Targets ◽  
Viral Infections ◽  
Interaction Analysis ◽  
Human Interaction ◽  
Host Cells ◽  
Phosphorylation Sites ◽  
Human Viruses ◽  
Disordered Regions

Abstract In viruses, posttranslational modifications (PTMs) are essential for their life cycle. Recognizing viral PTMs is very important for a better understanding of the mechanism of viral infections and finding potential drug targets. However, few studies have investigated the roles of viral PTMs in virus–human interactions using comprehensive viral PTM datasets. To fill this gap, we developed the first comprehensive viral posttranslational modification database (VPTMdb) for collecting systematic information of PTMs in human viruses and infected host cells. The VPTMdb contains 1240 unique viral PTM sites with 8 modification types from 43 viruses (818 experimentally verified PTM sites manually extracted from 150 publications and 422 PTMs extracted from SwissProt) as well as 13 650 infected cells’ PTMs extracted from seven global proteomics experiments in six human viruses. The investigation of viral PTM sequences motifs showed that most viral PTMs have the consensus motifs with human proteins in phosphorylation and five cellular kinase families phosphorylate more than 10 viral species. The analysis of protein disordered regions presented that more than 50% glycosylation sites of double-strand DNA viruses are in the disordered regions, whereas single-strand RNA and retroviruses prefer ordered regions. Domain–domain interaction analysis indicating potential roles of viral PTMs play in infections. The findings should make an important contribution to the field of virus–human interaction. Moreover, we created a novel sequence-based classifier named VPTMpre to help users predict viral protein phosphorylation sites. VPTMdb online web server (http://vptmdb.com:8787/VPTMdb/) was implemented for users to download viral PTM data and predict phosphorylation sites of interest.

Regulation of the water channel aquaporin-2 by posttranslational modification

2011 ◽  
Vol 300 (5) ◽  
pp. F1062-F1073 ◽  
Author(s):  
Hanne B. Moeller ◽  
Emma T. B. Olesen ◽  
Robert A. Fenton
Keyword(s):  
Membrane Proteins ◽  
Protein Interactions ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Water Channel ◽  
Cellular Functions ◽  
Aquaporin 2 ◽  
Eukaryotic Membrane Proteins ◽  
Insight Into

The cellular functions of many eukaryotic membrane proteins, including the vasopressin-regulated water channel aquaporin-2 (AQP2), are regulated by posttranslational modifications. In this article, we discuss the experimental discoveries that have advanced our understanding of how posttranslational modifications affect AQP2 function, especially as they relate to the role of AQP2 in the kidney. We review the most recent data demonstrating that glycosylation and, in particular, phosphorylation and ubiquitination are mechanisms that regulate AQP2 activity, subcellular sorting and distribution, degradation, and protein interactions. From a clinical perspective, posttranslational modification resulting in protein misrouting or degradation may explain certain forms of nephrogenic diabetes insipidus. In addition to providing major insight into the function and dynamics of renal AQP2 regulation, the analysis of AQP2 posttranslational modification may provide general clues as to the role of posttranslational modification for regulation of other membrane proteins.

scholarly journals The CTCF Insulator Protein Is Posttranslationally Modified by SUMO

2008 ◽  
Vol 29 (3) ◽  
pp. 714-725 ◽  
Author(s):  
Melissa J. MacPherson ◽  
Linda G. Beatty ◽  
Wenjing Zhou ◽  
Minjie Du ◽  
Paul D. Sadowski
Keyword(s):  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Zinc Finger Protein ◽  
Finger Protein ◽  
Ability To Act ◽  
Polycomb Protein ◽  
P2 Promoter ◽  
Polycomb Bodies

ABSTRACT The CTCF protein is a highly conserved zinc finger protein that is implicated in many aspects of gene regulation and nuclear organization. Its functions include the ability to act as a repressor of genes, including the c-myc oncogene. In this paper, we show that the CTCF protein can be posttranslationally modified by the small ubiquitin-like protein SUMO. CTCF is SUMOylated both in vivo and in vitro, and we identify two major sites of SUMOylation in the protein. The posttranslational modification of CTCF by the SUMO proteins does not affect its ability to bind to DNA in vitro. SUMOylation of CTCF contributes to the repressive function of CTCF on the c-myc P2 promoter. We also found that CTCF and the repressive Polycomb protein, Pc2, are colocalized to nuclear Polycomb bodies. The Pc2 protein may act as a SUMO E3 ligase for CTCF, strongly enhancing its modification by SUMO 2 and 3. These studies expand the repertoire of posttranslational modifications of CTCF and suggest roles for such modifications in its regulation of epigenetic states.

scholarly journals Phosphorylation of huntingtin at residue T3 is decreased in Huntington’s disease and modulates mutant huntingtin protein conformation

2017 ◽  
Vol 114 (50) ◽  
pp. E10809-E10818 ◽  
Author(s):  
Cristina Cariulo ◽  
Lucia Azzollini ◽  
Margherita Verani ◽  
Paola Martufi ◽  
Roberto Boggio ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Protein Conformation ◽  
Clinical Samples ◽  
Biophysical Properties ◽  
Mutant Huntingtin Protein ◽  
Exon 1 ◽  
Bona Fide

Posttranslational modifications can have profound effects on the biological and biophysical properties of proteins associated with misfolding and aggregation. However, their detection and quantification in clinical samples and an understanding of the mechanisms underlying the pathological properties of misfolding- and aggregation-prone proteins remain a challenge for diagnostics and therapeutics development. We have applied an ultrasensitive immunoassay platform to develop and validate a quantitative assay for detecting a posttranslational modification (phosphorylation at residue T3) of a protein associated with polyglutamine repeat expansion, namely Huntingtin, and characterized its presence in a variety of preclinical and clinical samples. We find that T3 phosphorylation is greatly reduced in samples from Huntington’s disease models and in Huntington’s disease patients, and we provide evidence that bona-fide T3 phosphorylation alters Huntingtin exon 1 protein conformation and aggregation properties. These findings have significant implications for both mechanisms of disease pathogenesis and the development of therapeutics and diagnostics for Huntington’s disease.

scholarly journals Posttranslational modification of tubulin by palmitoylation: I. In vivo and cell-free studies.

1997 ◽  
Vol 8 (4) ◽  
pp. 621-636 ◽  
Author(s):  
J M Caron
Keyword(s):  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Hydrophobic Interactions ◽  
Covalent Attachment ◽  
Protein Structure Analysis ◽  
Free System ◽  
Intracellular Membranes ◽  
Cell Free System ◽  
Cytoplasmic Proteins

It is well established that microtubules interact with intracellular membranes of eukaryotic cells. There is also evidence that tubulin, the major subunit of microtubules, associates directly with membranes. In many cases, this association between tubulin and membranes involves hydrophobic interactions. However, neither primary sequence nor known posttranslational modifications of tubulin can account for such an interaction. The goal of this study was to determine the molecular nature of hydrophobic interactions between tubulin and membranes. Specifically, I sought to identify a posttranslational modification of tubulin that is found in membrane proteins but not in cytoplasmic proteins. One such modification is the covalent attachment of the long chain fatty acid palmitate. The possibility that tubulin is a substrate for palmitoylation was investigated. First, I found that tubulin was palmitoylated in resting platelets and that the level of palmitoylation of tubulin decreased upon activation of platelets with thrombin. Second, to obtain quantities of palmitoylated tubulin required for protein structure analysis, a cell-free system for palmitoylation of tubulin was developed and characterized. The substrates for palmitoylation were nonpolymerized tubulin and tubulin in microtubules assembled with the slowly hydrolyzable GTP analogue guanylyl-(alpha, beta)-methylene-diphosphonate. However, tubulin in Taxol-assembled microtubules was not a substrate for palmitoylation. Likewise, palmitoylation of tubulin in the cell-free system was specifically inhibited by the antimicrotubule drugs Colcemid, podophyllotoxin, nocodazole, and vinblastine. These experiments identify a previously unknown posttranslational modification of tubulin that can account for at least one type of hydrophobic interaction with intracellular membranes.

scholarly journals The Role of Posttranslational Modification and Mitochondrial Quality Control in Cardiovascular Diseases

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jinlin Liu ◽  
Li Zhong ◽  
Rui Guo
Keyword(s):  
Quality Control ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Protein Function ◽  
Therapeutic Potential ◽  
Normal Function ◽  
Future Research ◽  
Mitochondrial Quality Control ◽  
Mitochondrial Homeostasis

Cardiovascular disease (CVD) is the leading cause of death in the world. The mechanism behind CVDs has been studied for decades; however, the pathogenesis is still controversial. Mitochondrial homeostasis plays an essential role in maintaining the normal function of the cardiovascular system. The alterations of any protein function in mitochondria may induce abnormal mitochondrial quality control and unexpected mitochondrial dysfunction, leading to CVDs. Posttranslational modifications (PTMs) affect protein function by reversibly changing their conformation. This review summarizes how common and novel PTMs influence the development of CVDs by regulating mitochondrial quality control. It provides not only ideas for future research on the mechanism of some types of CVDs but also ideas for CVD treatments with therapeutic potential.

scholarly journals The FAT10 Posttranslational Modification Is Involved in Lytic Replication of Kaposi’s Sarcoma-Associated Herpesvirus

2021 ◽  
Vol 95 (10) ◽  
Author(s):  
Atsuko Sugimoto ◽  
Yuichi Abe ◽  
Tadashi Watanabe ◽  
Kohei Hosokawa ◽  
Jun Adachi ◽  
...  
Keyword(s):  
Protein Expression ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Kaposi's Sarcoma ◽  
Virus Production ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT During Kaposi’s sarcoma-associated herpesvirus (KSHV) lytic replication, host cell functions, including protein expression and posttranslational modification pathways, are dysregulated by KSHV to promote virus production. Here, we attempted to identify key proteins for KSHV lytic replication by profiling protein expression in the latent and lytic phases using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Proteomic analysis, immunoblotting, and quantitative PCR demonstrated that antigen F (HLA-F) adjacent transcript 10 (FAT10) and UBE1L2 (also known as ubiquitin-like modifier-activating enzyme 6 [UBA6]) were upregulated during lytic replication. FAT10 is a ubiquitin-like protein (UBL). UBE1L2 is the FAT10-activating enzyme (E1), which is essential for FAT10 modification (FAT10ylation). FAT10ylated proteins were immediately expressed after lytic induction and increased over time during lytic replication. Knockout of UBE1L2 suppressed KSHV production but not KSHV DNA synthesis. In order to isolate FAT10ylated proteins during KSHV lytic replication, we conducted immunoprecipitation using anti-FAT10 antibody and nickel-nitrilotriacetic acid (Ni-NTA) chromatography of exogenously expressed His-tagged FAT10 from cells undergoing latent or lytic replication. LC-MS/MS was performed to identify FAT10ylated proteins. We identified KSHV ORF59 and ORF61 as FAT10ylation substrates. Our study revealed that the UBE1L2-FAT10 system is upregulated during KSHV lytic replication, and it contributes to viral propagation. IMPORTANCE Ubiquitin and UBL posttranslational modifications, including FAT10, are utilized and dysregulated by viruses for achievement of effective infection and virion production. The UBE1L2-FAT10 system catalyzes FAT10ylation, where one or more FAT10 molecules are covalently linked to a substrate. FAT10ylation is catalyzed by the sequential actions of E1 (activation enzyme), E2 (conjugation enzyme), and E3 (ligase) enzymes. The E1 enzyme for FAT10ylation is UBE1L2, which activates FAT10 and transfers it to E2/USE1. FAT10ylation regulates the cell cycle, interferon (IFN) signaling, and protein degradation; however, its primary biological function remains unknown. Here, we revealed that KSHV lytic replication induces UBE1L2 expression and production of FAT10ylated proteins, including KSHV lytic proteins. Moreover, UBE1L2 knockout suppressed virus production during the lytic cycle. This is the first report demonstrating the contribution of the UBE1L2-FAT10 system to KSHV lytic replication. Our findings provide insight into the physiological function(s) of novel posttranslational modifications in KSHV lytic replication.

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