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Structure and Function of Membrane Proteins 2.0

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Biochemistry".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 7202

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Special Issue Editor

Prof. Dr. Larry Fliegel

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Guest Editor

Department of Biochemistry, Faculty of Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
Interests: membrane proteins; pH regulation; Na⁺/H⁺ exchanger
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

While we now have much information on the human genome, we still know little about the structure and function of many proteins, or how they function in health and disease. Genome sequencing projects show that, in humans, up to 45% of all proteins are embedded in or cross a membrane. The involvement of membrane proteins in disease is unquestionable, and includes relatively common diseases such as muscular dystrophy and cystic fibrosis. Until relatively recently, only a small fraction of the proteins that have been analyzed in any detail, or had their structure elucidated, are membrane proteins. Recent advances in technology including cryo-electron microscopy, protein production and other techniques, have greatly improved our understanding of membrane proteins.

This Special Issue on “Structure and Function of Membrane Proteins” aims to provide a summary of the emerging field with emphasis on novel developments in the field and novel results with different types of membrane proteins. The Special Issue calls for original research, mini and full reviews, including perspectives in the field of the current standing of membrane protein biology. Papers on structure and function of membrane proteins, mechanisms of transport and the role of structural and functional changes in disease are welcome.

Prof. Dr. Larry Fliegel
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (4 papers)

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Editorial

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5 pages, 198 KiB

Open AccessEditorial

Structure and Function of Membrane Proteins

by Larry Fliegel

Int. J. Mol. Sci. 2023, 24(9), 8350; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms24098350 - 06 May 2023

Cited by 1 | Viewed by 1124

Abstract

While we have a great deal of information on the human genome, in many cases we still know little about the structure’s function, the regulation of membrane proteins and how they are altered in health and disease [...] Full article

(This article belongs to the Special Issue Structure and Function of Membrane Proteins 2.0)

Research

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12 pages, 3199 KiB

Open AccessArticle

PEDF Protects Endothelial Barrier Integrity during Acute Myocardial Infarction via 67LR

by Jingtian Liang, Qifeng Luo, Ningning Shen, Xichun Qin, Caili Jia, Zhixiang Chao, Li Zhang, Hao Qin, Xiucheng Liu, Xiaoyu Quan, Yanliang Yuan and Hao Zhang

Int. J. Mol. Sci. 2023, 24(3), 2787; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms24032787 - 01 Feb 2023

Cited by 4 | Viewed by 1349

Abstract

Maintaining the integrity and protecting the stability of tight junctions in endothelial cells is a potential therapeutic strategy against myocardial ischaemia. Laminin receptors (67LR) are highly expressed on endothelial cell membranes and are associated with endothelial barrier function. Herein, we sought to demonstrate the direct effects of pigment epithelial-derived factor (PEDF) on tight junctions between endothelial cells via 67LR during acute myocardial infarction (AMI) and elucidate its underlying mechanisms. We detected that PEDF directly increased the level of the tight junction protein zonula occludens protein 1 (ZO-1) after overexpression in vitro and in vivo using Western blotting. Evans Blue/TTC staining showed that PEDF significantly reduced the size of the infarcted myocardium. Immunofluorescence and the transwell cellular experiments suggested that PEDF significantly upregulated PI3K-AKT permeability and the distribution of ZO-1 between endothelial cells under OGD conditions. Interestingly, PEDF significantly upregulated the phosphorylation levels of PI3K-AKT-mTOR under oxygen and glucose deprivation conditions but had no significant effects on the total protein expression. The protective effect of PEDF on ZO-1 was significantly inhibited following the inhibition of PI3K-AKT-mTOR. The activation of phosphorylation of PI3K-AKT-mTOR by PEDF was blocked after silencing 67LR, as were the protective effects of PEDF on ZO-1. Therefore, we have reason to believe that PEDF increased ZO-1 expression through the 67LR-dependent PI3K-AKT-mTOR signaling pathway, thus maintaining tight junction stability and protecting cardiac function. Full article

(This article belongs to the Special Issue Structure and Function of Membrane Proteins 2.0)

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17 pages, 3886 KiB

Open AccessArticle

The Magnetosome Protein, Mms6 from Magnetospirillum magneticum Strain AMB-1, Is a Lipid-Activated Ferric Reductase

by Dilini Singappuli-Arachchige, Shuren Feng, Lijun Wang, Pierre E. Palo, Samuel O. Shobade, Michelle Thomas and Marit Nilsen-Hamilton

Int. J. Mol. Sci. 2022, 23(18), 10305; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms231810305 - 07 Sep 2022

Cited by 2 | Viewed by 1941

Abstract

Magnetosomes of magnetotactic bacteria consist of magnetic nanocrystals with defined morphologies enclosed in vesicles originated from cytoplasmic membrane invaginations. Although many proteins are involved in creating magnetosomes, a single magnetosome protein, Mms6 from Magnetospirillum magneticum strain AMB-1, can direct the crystallization of magnetite nanoparticles in vitro. The in vivo role of Mms6 in magnetosome formation is debated, and the observation that Mms6 binds Fe³⁺ more tightly than Fe²⁺ raises the question of how, in a magnetosome environment dominated by Fe³⁺, Mms6 promotes the crystallization of magnetite, which contains both Fe³⁺ and Fe²⁺. Here we show that Mms6 is a ferric reductase that reduces Fe³⁺ to Fe²⁺ using NADH and FAD as electron donor and cofactor, respectively. Reductase activity is elevated when Mms6 is integrated into either liposomes or bicelles. Analysis of Mms6 mutants suggests that the C-terminal domain binds iron and the N-terminal domain contains the catalytic site. Although Mms6 forms multimers that involve C-terminal and N-terminal domain interactions, a fusion protein with ubiquitin remains a monomer and displays reductase activity, which suggests that the catalytic site is fully in the monomer. However, the quaternary structure of Mms6 appears to alter the iron binding characteristics of the C-terminal domain. These results are consistent with a hypothesis that Mms6, a membrane protein, promotes the formation of magnetite in vivo by a mechanism that involves reducing iron. Full article

(This article belongs to the Special Issue Structure and Function of Membrane Proteins 2.0)

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Review

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23 pages, 1714 KiB

Open AccessReview

Prokaryotic Na⁺/H⁺ Exchangers—Transport Mechanism and Essential Residues

by Miyer Patiño-Ruiz, Constanța Ganea and Octavian Călinescu

Int. J. Mol. Sci. 2022, 23(16), 9156; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23169156 - 15 Aug 2022

Cited by 9 | Viewed by 2131

Abstract

Na⁺/H⁺ exchangers are essential for Na⁺ and pH homeostasis in all organisms. Human Na⁺/H⁺ exchangers are of high medical interest, and insights into their structure and function are aided by the investigation of prokaryotic homologues. Most prokaryotic Na⁺/H⁺ exchangers belong to either the Cation/Proton Antiporter (CPA) superfamily, the Ion Transport (IT) superfamily, or the Na⁺-translocating Mrp transporter superfamily. Several structures have been solved so far for CPA and Mrp members, but none for the IT members. NhaA from E. coli has served as the prototype of Na⁺/H⁺ exchangers due to the high amount of structural and functional data available. Recent structures from other CPA exchangers, together with diverse functional information, have allowed elucidation of some common working principles shared by Na⁺/H⁺ exchangers from different families, such as the type of residues involved in the substrate binding and even a simple mechanism sufficient to explain the pH regulation in the CPA and IT superfamilies. Here, we review several aspects of prokaryotic Na⁺/H⁺ exchanger structure and function, discussing the similarities and differences between different transporters, with a focus on the CPA and IT exchangers. We also discuss the proposed transport mechanisms for Na⁺/H⁺ exchangers that explain their highly pH-regulated activity profile. Full article

(This article belongs to the Special Issue Structure and Function of Membrane Proteins 2.0)

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