435:
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11;12;15 triple mutant which lacked activity in each of the three genes. This triple mutant was shown to have delayed embryo development; that is, the seeds of the triple mutant were significantly smaller than that of the wild type at the same time during development. The starch content of the seed
442:
Many bacterial homologues have only 3 TMSs and are half sized, but they nevertheless are members of the SWEET family with a single 3 TMS repeat unit. Other bacterial homologues have 7 TMSs as do most eukaryotic proteins in this family. The SWEET family is large and diverse. Based on 3-D structural
446:
Bacterial SemiSWEETs, consist of a triple-helix bundle in a 1-3-2 conformation, with TM3 sandwiched between TM1 and TM2. The structures also show tryptophan and asparagine residues interacting with the sugar; point mutations of these residues to alanine destroys the hexose transport function of
403:
led to corresponding loss of and increase in nectar secretion, respectively. After showing that SWEET9 is involved in nectar secretion, the next step was to determine at which phase of the process SWEET9 has its function. The 3 options were: phloem unloading, or uptake or efflux from nectary
302:(ER). Glucose movement from the cytoplasm to the ER of the HEK293T cells was monitored by quantifying changes in FRET ratio. By using this assay, the first member of the SWEET family, AtSWEET1, was identified. Other potential family members were identified by sequence homology.
412:
Chen et al., 2015, asked what SWEETs are involved in providing nutrition to an embryo. The team noticed that mRNA and protein for SWEETs 11, 12, and 15 are each expressed at high levels during some stage of embryo development. Each gene was subsequently mutated to generate a
290:, in a screen for novel facilitators of transmembrane glucose transport. In this experiment, several previously uncharacterized membrane proteins were selected to be screened. These uncharacterized membrane proteins were assayed for glucose transport ability by expression in
398:
Lin et al., 2014, examined the role of SWEET9 in nectaries. SWEET9 is a member of clade 3. A homologue in petunias had been shown to have an inverse correlation between expression and starch content in nectaries. Mutation and overexpression of SWEET9 in
956:
Sosso D, Luo D, Li QB, Sasse J, Yang J, Gendrot G, Suzuki M, Koch KE, McCarty DR, Chourey PS, Rogowsky PM, Ross-Ibarra J, Yang B, Frommer WB (December 2015). "Seed filling in domesticated maize and rice depends on SWEET-mediated hexose transport".
1035:
Lin IW, Sosso D, Chen LQ, Gase K, Kim SG, Kessler D, Klinkenberg PM, Gorder MK, Hou BH, Qu XQ, Carter CJ, Baldwin IT, Frommer WB (April 2014). "Nectar secretion requires sucrose phosphate synthases and the sugar transporter SWEET9".
850:
Hou BH, Takanaga H, Grossmann G, Chen LQ, Qu XQ, Jones AM, Lalonde S, Schweissgut O, Wiechert W, Frommer WB (October 2011). "Optical sensors for monitoring dynamic changes of intracellular metabolite levels in mammalian cells".
1284:
Hamada M, Wada S, Kobayashi K, Satoh N (September 2005). "Ci-Rga, a gene encoding an MtN3/saliva family transmembrane protein, is essential for tissue differentiation during embryogenesis of the ascidian Ciona intestinalis".
1439:
899:
Chen LQ, Hou BH, Lalonde S, Takanaga H, Hartung ML, Qu XQ, Guo WJ, Kim JG, Underwood W, Chaudhuri B, Chermak D, Antony G, White FF, Somerville SC, Mudgett MB, Frommer WB (November 2010).
310:
Chen et al. (2010) reviewed evidence for a new class of sugar transporters, named SWEETs. Those that mediate glucose transport include at least six out of seventeen sugar homologues in
418:
coat was higher than the wild-type, and the starch content of the embryo was lower than the wild-type. Additionally, protein levels were shown to be maternally controlled: in a
664:
Bermejo C, Ewald JC, Lanquar V, Jones AM, Frommer WB (August 2011). "In vivo biochemistry: quantifying ion and metabolite levels in individual cells or cultures of yeast".
154:
294:(human embryonic kidney) cells, which have negligible glucose transport ability in the normal state. These membrane proteins were co-expressed with a fluorescent
404:
parenchyma. A combination of localization studies and starch accumulation assays showed that SWEET9 is involved in sucrose efflux from the nectary parenchyma.
1443:
1000:
Feng CY, Han JX, Han XX, Jiang J (December 2015). "Genome-wide identification, phylogeny, and expression analysis of the SWEET gene family in tomato".
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Ge YX, Angenent GC, Wittich PE, Peters J, Franken J, Busscher M, Zhang LM, Dahlhaus E, Kater MM, Wullems GJ, Creemers-Molenaar T (December 2000).
110:
98:
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3.1 A resolution structure of a eukaryotic SWEET transporter in a homotrimer (5CTG, OsSWEET2). Each different color represents one subunit.
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Proteins of the SWEET family appear to catalyze facilitated diffusion (entry or export) of sugars across the plant plasma membrane or the
1089:"A cascade of sequentially expressed sucrose transporters in the seed coat and endosperm provides nutrition for the Arabidopsis embryo"
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SWEET8 (TC# 2.A.123.1.5), pollen is not viable. The corn homolog ZmSWEET4c was shown to be involved in seed filling.
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Kanno Y, Oikawa T, Chiba Y, Ishimaru Y, Shimizu T, Sano N, Koshiba T, Kamiya Y, Ueda M, Seo M (October 2016).
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79:
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1316:"Novel genes involved in Ciona intestinalis embryogenesis: characterization of gene knockdown embryos"
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Okumoto S, Jones A, Frommer WB (1 January 2012). "Quantitative imaging with fluorescent biosensors".
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Chen LQ, Lin IW, Qu XQ, Sosso D, McFarlane HE, Londoño A, Samuels AL, Frommer WB (March 2015).
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Tao Y, Cheung LS, Li S, Eom JS, Chen LQ, Xu Y, Perry K, Frommer WB, Feng L (November 2015).
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Xu Y, Tao Y, Cheung LS, Fan C, Chen LQ, Xu S, Perry K, Frommer WB, Feng L (November 2014).
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analyses, it is likely that these paired 3 TMS SWEET family members function as carriers.
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1141:"Structures of bacterial homologues of SWEET transporters in two distinct conformations"
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Yee DC, Shlykov MA, Västermark A, Reddy VS, Arora S, Sun EI, Saier MH (November 2013).
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Jones AM, Grossmann G, Danielson JÅ, Sosso D, Chen LQ, Ho CH, Frommer WB (June 2013).
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709:"In vivo biochemistry: applications for small molecule biosensors in plant biology"
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Currently classified members of the SWEET transporter family can be found in the
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584:"AtSWEET13 and AtSWEET14 regulate gibberellin-mediated physiological processes"
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mutant crossed with a wild-type plant, the mutant phenotype was only seen when
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1251:"NEC1, a novel gene, highly expressed in nectary tissue of Petunia hybrida"
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901:"Sugar transporters for intercellular exchange and nutrition of pathogens"
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The generalized reaction catalyzed by known proteins of this family is:
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As of 2 February 2016, this article is derived in whole or in part from
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1359:"Structure of a eukaryotic SWEET transporter in a homotrimeric complex"
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533:"Facilitative plasma membrane transporters function during ER transit"
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2 TMSs --> 4 TMSs --> 8 TMSs --> 7 TMSs --> 3 + 3 TMSs.
1446:. All relevant terms must be followed. The original text was at
1198:"The transporter-opsin-G protein-coupled receptor (TOG) superfamily"
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298:(Förster resonance energy transfer) glucose sensor localized to the
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They also seem to transport other metabolites, like gibberellins.
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766:"A never ending race for new and improved fluorescent proteins"
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for members of the SWEET/SemiSWEET/PQ-loop/Saliva/MtN3 family.
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1448:"2.A.123 The Sweet; PQ-loop; Saliva; MtN3 (Sweet) Family"
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514:"2.A.123 The Sweet; PQ-loop; Saliva; MtN3 (Sweet) Family"
226:), is a family of sugar transporters and a member of the
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230:. The proteins of the SWEET family have been found in
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Hamada M, Wada S, Kobayashi K, Satoh N (July 2007).
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451:which is believed to have arisen via the pathway:
1287:Differentiation; Research in Biological Diversity
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447:SemiSWEET. The SWEET family is a member of the
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764:Jones AM, Ehrhardt DW, Frommer WB (May 2012).
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457:Several crystal structures are available on
640:"Nanosensors | Department of Plant Biology"
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408:SWEETs 11, 12, and 15 in Embryo Nutrition
520:. Saier Lab Bioinformatics Group / SDSC.
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390:. The tomato genome encodes 29 SWEETs.
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531:Takanaga H, Frommer WB (August 2010).
250:(TMSs) in a 3+1+3 repeat arrangement.
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354:) and the single copy human protein (
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286:SWEETs were originally identified in
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377:Transporter Classification Database.
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518:Transporter Classification Database
481:Transporter Classification Database
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246:. Eukaryotic family members have 7
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344:), two out of seven homologues in
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1299:10.1111/j.1432-0436.2005.00037.x
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713:Current Opinion in Plant Biology
426:was used as the maternal plant.
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817:Annual Review of Plant Biology
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126:Available protein structures:
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386:Plant SWEETs fall into four
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394:SWEET9 in Nectar Secretion
277:sugars (in) ⇌ sugars (out)
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1320:Developmental Dynamics
1105:10.1105/tpc.114.134585
865:10.1038/nprot.2011.392
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347:Caenorhabditis elegans
248:transmembrane segments
1463:Solute carrier family
471:Solute carrier family
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300:endoplasmic reticulum
260:endoplasmic reticulum
550:10.1096/fj.09-146472
288:Arabidopsis thaliana
1383:10.1038/nature15391
1375:2015Natur.527..259T
1165:10.1038/nature13670
1157:2014Natur.515..448X
1058:10.1038/nature13082
1050:2014Natur.508..546L
925:10.1038/nature09606
917:2010Natur.468..527C
725:2013COPB...16..389J
608:10.1038/ncomms13245
600:2016NatCo...713245K
486:Glucose transporter
1333:10.1002/dvdy.21181
1214:10.1111/febs.12499
678:10.1042/BJ20110428
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1369:(7577): 259–263.
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316:(i.e., TC#s
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188:SWEET family
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823:: 663–706.
770:BMC Biology
672:(1): 1–10.
401:Arabidopsis
370:Arabidopsis
368:). Without
350:(i.e., TC#
338:2.A.123.1.6
326:2.A.123.1.9
322:2.A.123.1.5
318:2.A.123.1.3
313:Arabidopsis
224:TC# 2.A.123
220:MtN3 family
111:OPM protein
24:Identifiers
1457:Categories
588:Nat Commun
497:References
306:Homologues
262:membrane.
240:protozoans
138:structures
430:Structure
388:subclades
282:Discovery
68:IPR006603
1401:26479032
1350:41944938
1342:17557306
1307:16219040
1277:11135107
1232:23981446
1183:25186729
1123:25794936
1066:24670640
1022:26190159
979:26523777
943:21107422
881:21852318
873:22036884
837:22404462
802:22554191
751:23587939
694:26944897
686:21793803
626:27782132
569:20354141
465:See also
254:Function
244:bacteria
206:xported
155:RCSB PDB
63:InterPro
1425:Biology
1392:4734654
1371:Bibcode
1223:3832197
1174:4300204
1153:Bibcode
1114:4558658
1074:4384123
1046:Bibcode
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