[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-327067-105":3,"detail-sidebar-cat-0-en-105":81,"doc-detail-327067-en":130},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","abc-transporters-overview-of-major-physiological-and-biochemical-functions-and-structural-properties","ABC TRANSPORTERS - overview of major physiological and biochemical functions and structural properties","","ABC proteins form the largest protein family across Archaea to Homo sapiens, reaching up to about 4% of bacterial genomes and dozens of members in eukaryotes. They share a consensus ATP-binding region with Walker A and B motifs and often function in transport-related physiological roles. The text details ABC transporter topology, comparing half-sized and full-sized organizations (TMD–NBD arrangements) and bacterial periplasmic receptor associations. It further summarizes phylogeny, ATP-driven substrate transport directionality, and transporter classification within the TC system, including well-known prokaryotic and eukaryotic efflux families such as MDR1/Pgp.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/research-report/","Research & 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structural feature identifies ABC proteins as a family?","Question",{"text":63,"@type":64},"ABC proteins are recognized by a consensus ATP-binding region of about 100 amino acids that includes the Walker A and B motifs plus a linker C region.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How are ABC transporters organized in eukaryotes versus bacteria?",{"text":68,"@type":64},"Eukaryotic full-sized ABC transporters commonly associate two TMDs and two NBDs in one molecule, whereas bacterial systems often pair NBDs with TMDs as separate or fused subunits, sometimes along with additional associated proteins.",{"name":70,"@type":61,"acceptedAnswer":71},"How does the TC system relate to ABC transporter phylogeny and classification?",{"text":72,"@type":64},"Within the ABC superfamily, phylogenetic families generally correlate with substrate specificity, and classification is performed using functional and phylogenetic criteria in the transporter classification (TC) system originally developed by Milton Saier.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},327067,1790198787,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,101,106,111,115,119,122,126],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & 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Cup","world-cup",{"id":123,"doc_module":4,"doc_module_name":25,"category_name":124,"show_sort_weight":123,"slug":125},10,"Lifestyle","lifestyle",{"id":127,"doc_module":4,"doc_module_name":25,"category_name":128,"show_sort_weight":97,"slug":129},19,"General","general",{"code":4,"msg":82,"data":131},{"doc_id":79,"user_id":132,"nickname":42,"user_avatar":133,"doc_module":4,"category_id":112,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":139,"language":140,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":12,"update_tm":144,"read_time":145,"preview_page_count":4},687197207919,"https://ap-avatar.wpscdn.com/avatar/a000253d6f5f7c60be?x-image-process=image/resize,m_fixed,w_180,h_180&k=1779446848396160552","a ABC Transporters  \nAndr´e Goffeau, Benoˆıt De Hertogh and Philippe V. Baret Universit´e Catholique de Louvain, Louvain-la-Neuve, Belgium  \nThe ABC proteins constitute the largest family of proteins. They are present in all living species from Archaea to Homo sapiens. They make up to 4% of the full genome complement of bacteria such as Escherichia coli or Bacillus subtilis. Each eukaryote genome contains several dozens of members (over 100 in the plant Arabidopsis thaliana). They are recognized by a consensus ATP-binding region of approximately 100 amino acids which include the two Walker A and B motifs encompassing a linker or C region (Figure 1). The ABC proteins catalyze a wide variety of physiological functions, most (but not all) of which being related to transport. This article describes the major physiological and biochemical functions as well as the structural properties of some of the best-known ABC transporters using examples from the yeast Saccharomyces cerevisiae and Homo sapiens.  \nTopology  \nMost, but not all, ABC proteins are ABC transporters. Each of those molecules contains, or is associated to, one or two cytoplasmic ATP-binding domains named nucleotide binding domains (NBDs) (Figure 1) and one or two transmembrane domains (TMDs) (Figure 2) . Each TMD comprises usually six a-helix spans. Association of one TMD to one NBD results in a half-size ABC transporter; however, they are believed to function as homo- or heterodimers so that the minimal functional organization of an ABC transporter is considered to be TMD–NBD– TMD–NBD or NBD–TMD–NBD–TMD. In eukaryotes, two TMDs and two NBDs are often associated in one single molecule called full-sized ABC transporter. The topological relation between NBD(s) and TMDs is variable (Figure 2) . In bacteria two NBDs often associate with two TMDs either as four single subunits encoded by the same operon or in various combinations of fused subunits. Association of other proteins may occur. The most prominent associated bacterial protein is the periplasmic solute-binding receptor, which in gramnegative bacteria is found in the periplasm, and ingram-positive bacteria is present often as a lipoprotein, bound to the external membrane surface via electrostatic interactions (Figure 3). The three domains ofthe bacterial ABC uptake transporters: namely the periplasmic  \nbinding receptor, the cytoplasmic NDB, and the membrane TMD are believed to have arisen from a common ancestral ABC transporter in which these three proteins were already present. However, during evolution, the sequence of the periplasmic solute-binding receptors diverges more rapidly than that of the TMDs, while that of NBDs is the least divergent. Thus, all NBDs are homologous, but this is not true for the TMDs orthe receptors. Nevertheless, the phylogenetic clustering patterns in bacterial ABC from different species are generally the same for all three types of proteins, despite their variable rate of evolution.  \nThe topology of some eukaryotic ABC effluxers can be complex as additional TM spans occur in some systems (Figure 3) as well as extra cytoplasmic domains of presumed regulatory function.  \nPhylogeny  \nThe different families of ABC proteins transport a wide variety of substrates against their concentration gradient using the energy of ATP hydrolysis carried out by NBD. In bacteria, the transported substrates are either imported in or exported out of the cell. In eukaryotes, only extracytoplasmic exporters (transporting substrates either out of the cell or into organelles) are known up to now. Within the ABC superfamily, 61 phylogenetic families have been identified so far. These families generally correlate with substrate specificity. Their classification based both on functional and phylogenetic criteria has been carried out within the transporter classification (TC) system developed by Milton Saier in San Diego. The TC system has recently been endorsed by The International Union of the Biochemical and Molecul","cbCailq7IcI2Ygdv","https://ap.wps.com/l/cbCailq7IcI2Ygdv","pdf",25617614,895,"English","# Topology\n## Domain organization and transporter forms\n## Bacterial uptake and associated receptors\n# Phylogeny\n## ATP-driven transport and substrate families\n## TC classification and notable examples","[{\"question\":\"What structural feature identifies ABC proteins as a family?\",\"answer\":\"ABC proteins are recognized by a consensus ATP-binding region of about 100 amino acids that includes the Walker A and B motifs plus a linker C region.\"},{\"question\":\"How are ABC transporters organized in eukaryotes versus bacteria?\",\"answer\":\"Eukaryotic full-sized ABC transporters commonly associate two TMDs and two NBDs in one molecule, whereas bacterial systems often pair NBDs with TMDs as separate or fused subunits, sometimes along with additional associated proteins.\"},{\"question\":\"How does the TC system relate to ABC transporter phylogeny and classification?\",\"answer\":\"Within the ABC superfamily, phylogenetic families generally correlate with substrate specificity, and classification is performed using functional and phylogenetic criteria in the transporter classification (TC) system originally developed by Milton Saier.\"}]","ABC TRANSPORTERS - overview of major physiological and biochemical functions and structural properties | PDF",1789976169,2255]