Structure and Function of Cationic Amino Acid Transporters (CATs)

Devés, R., and C. A. R. Boyd. Transporters for Cationic Amino Acids in Animal Cells: Discovery, Structure, and Function. Physiol. Rev. 78: 487–545, 1998. — The structure and function of the four cationic amino acid transporters identified in animal cells are discussed. The systems differ in specificity, cation dependence, and physiological role. One of them, system y+, is selective for cationic amino acids, whereas the others (B0,+, b0,+, and y+L) also accept neutral amino acids. In recent years, cDNA clones related to these activities have been isolated. Thus two families of proteins have been identified: 1) CAT or cationic amino acid transporters and 2) BAT or broad-scope transport proteins. In the CAT family, three genes encode for four different isoforms [CAT-1, CAT-2A, CAT-2(B) and CAT-3]; these are ∼70-kDa proteins with multiple transmembrane segments ( 12 – 14 ), and despite their structural similarity, they differ in tissue distribution, kinetics, and regulatory properties. System y+is the expression of the activity of CAT transporters. The BAT family includes two isoforms (rBAT and 4F2hc); these are 59- to 78-kDa proteins with one to four membrane-spanning segments, and it has been proposed that these proteins act as transport regulators. The expression of rBAT and 4F2hc induces system b0,+and system y+L activity in Xenopus laevis oocytes, respectively. The roles of these transporters in nutrition, endocrinology, nitric oxide biology, and immunology, as well as in the genetic diseases cystinuria and lysinuric protein intolerance, are reviewed. Experimental strategies, which can be used in the kinetic characterization of coexpressed transporters, are also discussed.

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Structure and function of the acidic amino acid decarboxylase GADL1

10.26226/morressier.5b31ec572afeeb001345a1cc ◽

2018 ◽

Author(s):

Elaheh Mahootchi

Keyword(s):

Amino Acid ◽

Structure And Function ◽

Acid Decarboxylase ◽

Acidic Amino Acid ◽

Amino Acid Decarboxylase ◽

And Function

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Pichia pastoris and the Recombinant Human Heterodimeric Amino Acid Transporter 4F2hc-LAT1: From Clone Selection to Pure Protein

Methods and Protocols ◽

10.3390/mps4030051 ◽

2021 ◽

Vol 4 (3) ◽

pp. 51

Author(s):

Satish Kantipudi ◽

Daniel Harder ◽

Sara Bonetti ◽

Dimitrios Fotiadis ◽

Jean-Marc Jeckelmann

Keyword(s):

Amino Acid ◽

Pichia Pastoris ◽

Protein Complexes ◽

Amino Acid Transporter ◽

Amino Acid Transporters ◽

Expression Host ◽

Amino Acids And Derivatives ◽

Heterodimeric Complex ◽

Acid Transporter ◽

And Function

Heterodimeric amino acid transporters (HATs) are protein complexes composed of two subunits, a heavy and a light subunit belonging to the solute carrier (SLC) families SLC3 and SLC7. HATs transport amino acids and derivatives thereof across the plasma membrane. The human HAT 4F2hc-LAT1 is composed of the type-II membrane N-glycoprotein 4F2hc (SLC3A2) and the L-type amino acid transporter LAT1 (SLC7A5). 4F2hc-LAT1 is medically relevant, and its dysfunction and overexpression are associated with autism and tumor progression. Here, we provide a general applicable protocol on how to screen for the best membrane transport protein-expressing clone in terms of protein amount and function using Pichia pastoris as expression host. Furthermore, we describe an overexpression and purification procedure for the production of the HAT 4F2hc-LAT1. The isolated heterodimeric complex is pure, correctly assembled, stable, binds the substrate L-leucine, and is thus properly folded. Therefore, this Pichia pastoris-derived recombinant human 4F2hc-LAT1 sample can be used for downstream biochemical and biophysical characterizations.

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Characterization of the third member of the MCAT family of cationic amino acid transporters. Identification of a domain that determines the transport properties of the MCAT proteins.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)36854-1 ◽

1993 ◽

Vol 268 (28) ◽

pp. 20796-20800

Author(s):

E.I. Closs ◽

C.R. Lyons ◽

C Kelly ◽

J.M. Cunningham

Keyword(s):

Amino Acid ◽

Transport Properties ◽

Amino Acid Transporters ◽

Cationic Amino Acid ◽

The Third

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Chitosanase from Streptomyces sp. strain N174: a comparative review of its structure and function

Biochemistry and Cell Biology ◽

10.1139/o97-079 ◽

1997 ◽

Vol 75 (6) ◽

pp. 687-696 ◽

Cited By ~ 20

Author(s):

Tamo Fukamizo ◽

Ryszard Brzezinski

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Substrate Binding ◽

Structure And Function ◽

Site Directed Mutagenesis ◽

Directed Mutagenesis ◽

Amino Acid Residues ◽

Streptomyces Sp ◽

Binding Cleft ◽

And Function

Novel information on the structure and function of chitosanase, which hydrolyzes the beta -1,4-glycosidic linkage of chitosan, has accumulated in recent years. The cloning of the chitosanase gene from Streptomyces sp. strain N174 and the establishment of an efficient expression system using Streptomyces lividans TK24 have contributed to these advances. Amino acid sequence comparisons of the chitosanases that have been sequenced to date revealed a significant homology in the N-terminal module. From energy minimization based on the X-ray crystal structure of Streptomyces sp. strain N174 chitosanase, the substrate binding cleft of this enzyme was estimated to be composed of six monosaccharide binding subsites. The hydrolytic reaction takes place at the center of the binding cleft with an inverting mechanism. Site-directed mutagenesis of the carboxylic amino acid residues that are conserved revealed that Glu-22 and Asp-40 are the catalytic residues. The tryptophan residues in the chitosanase do not participate directly in the substrate binding but stabilize the protein structure by interacting with hydrophobic and carboxylic side chains of the other amino acid residues. Structural and functional similarities were found between chitosanase, barley chitinase, bacteriophage T4 lysozyme, and goose egg white lysozyme, even though these proteins share no sequence similarities. This information can be helpful for the design of new chitinolytic enzymes that can be applied to carbohydrate engineering, biological control of phytopathogens, and other fields including chitinous polysaccharide degradation. Key words: chitosanase, amino acid sequence, overexpression system, reaction mechanism, site-directed mutagenesis.

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Cysteine-Free Proteins in the Immunobiology of Arthropod-Borne Diseases

Journal of Biomedicine and Biotechnology ◽

10.1155/2010/171537 ◽

2010 ◽

Vol 2010 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

J. Santiago Mejia ◽

Erik N. Arthun ◽

Richard G. Titus

Keyword(s):

Plasmodium Falciparum ◽

Amino Acid ◽

Distribution Patterns ◽

Structural Features ◽

Structure And Function ◽

Cysteine Residues ◽

Distribution Analysis ◽

And Function ◽

Abundance And Distribution ◽

Host Parasite

One approach to identify epitopes that could be used in the design of vaccines to control several arthropod-borne diseases simultaneously is to look for common structural features in the secretome of the pathogens that cause them. Using a novel bioinformatics technique, cysteine-abundance and distribution analysis, we found that many different proteins secreted by several arthropod-borne pathogens, includingPlasmodium falciparum, Borrelia burgdorferi, and eight species of Proteobacteria, are devoid of cysteine residues. The identification of three cysteine-abundance and distribution patterns in several families of proteins secreted by pathogenic and nonpathogenic Proteobacteria, and not found when the amino acid analyzed was tryptophan, provides evidence of forces restricting the content of cysteine residues in microbial proteins during evolution. We discuss these findings in the context of protein structure and function, antigenicity and immunogenicity, and host-parasite relationships.

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Alterations in flight muscle ultrastructure and function in Drosophila tropomyosin mutants.

The Journal of Cell Biology ◽

10.1083/jcb.135.3.673 ◽

1996 ◽

Vol 135 (3) ◽

pp. 673-687 ◽

Cited By ~ 38

Author(s):

A J Kreuz ◽

A Simcox ◽

D Maughan

Keyword(s):

Amino Acid ◽

Power Output ◽

Flight Muscle ◽

Structure And Function ◽

Wild Type ◽

Muscle Tropomyosin ◽

Ultrastructure And Function ◽

And Function ◽

Net Power Output ◽

Current Report

Drosophila indirect flight muscle (IFM) contains two different types of tropomyosin: a standard 284-amino acid muscle tropomyosin, Ifm-TmI, encoded by the TmI gene, and two > 400 amino acid tropomyosins, TnH-33 and TnH-34, encoded by TmII. The two IFM-specific TnH isoforms are unique tropomyosins with a COOH-terminal extension of approximately 200 residues which is hydrophobic and rich in prolines. Previous analysis of a hypomorphic TmI mutant, Ifm(3)3, demonstrated that Ifm-TmI is necessary for proper myofibrillar assembly, but no null TmI mutant or TmII mutant which affects the TnH isoforms have been reported. In the current report, we show that four flightless mutants (Warmke et al., 1989) are alleles of TmI, and characterize a deficiency which deletes both TmI and TmII. We find that haploidy of TmI causes myofibrillar disruptions and flightless behavior, but that haploidy of TmII causes neither. Single fiber mechanics demonstrates that power output is much lower in the TmI haploid line (32% of wild-type) than in the TmII haploid line (73% of wild-type). In myofibers nearly depleted of Ifm-TmI, net power output is virtually abolished (< 1% of wild-type) despite the presence of an organized fibrillar core (approximately 20% of wild-type). The results suggest Ifm-TmI (the standard tropomyosin) plays a key role in fiber structure, power production, and flight, with reduced Ifm-TmI expression producing corresponding changes of IFM structure and function. In contrast, reduced expression of the TnH isoforms has an unexpectedly mild effect on IFM structure and function.

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Recent Advance in the Relationship between Excitatory Amino Acid Transporters and Parkinson’s Disease

Neural Plasticity ◽

10.1155/2016/8941327 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 16

Author(s):

Yunlong Zhang ◽

Feng Tan ◽

Pingyi Xu ◽

Shaogang Qu

Keyword(s):

Parkinson’S Disease ◽

Amino Acid ◽

Animal Models ◽

Substantia Nigra ◽

Excitatory Amino Acid ◽

Synaptic Cleft ◽

Dopamine Neurons ◽

Amino Acid Transporters ◽

Excitatory Amino Acid Transporters ◽

And Function

Parkinson’s disease (PD) is the most common movement disorder disease in the elderly and is characterized by degeneration of dopamine neurons and formation of Lewy bodies. Glutamate is the major excitatory neurotransmitter in the central nervous system (CNS). If glutamate is not removed promptly in the synaptic cleft, it will excessively stimulate the glutamate receptors and induce excitotoxic effects on the CNS. With lack of extracellular enzyme to decompose glutamate, glutamate uptake in the synaptic cleft is mainly achieved by the excitatory amino acid transporters (EAATs, also known as high-affinity glutamate transporters). Current studies have confirmed that decreased expression and function of EAATs appear in PD animal models. Moreover, single unilateral administration of EAATs inhibitor in the substantia nigra mimics several PD features and this is a solid evidence supporting that decreased EAATs contribute to the process of PD. Drugs or treatments promoting the expression and function of EAATs are shown to attenuate dopamine neurons death in the substantia nigra and striatum, ameliorate the behavior disorder, and improve cognitive abilities in PD animal models. EAATs are potential effective drug targets in treatment of PD and thus study of relationship between EAATs and PD has predominant medical significance currently.

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