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Information on EC 2.4.1.21 - starch synthase (glycosyl-transferring) and Organism(s) Oryza sativa and UniProt Accession B1B5Z1
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2.4.1.21 starch synthase (glycosyl-transferring)IUBMB Comments
The accepted name varies according to the source of the enzyme and the nature of its synthetic product, e.g. starch synthase, bacterial glycogen synthase. Similar to EC 2.4.1.11 [glycogen(starch) synthase] but the preferred or mandatory nucleoside diphosphate sugar substrate is ADP-alpha-D-glucose. The entry covers starch and glycogen synthases utilizing ADP-alpha-D-glucose.
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Word Map
- 2.4.1.21
- amylose
- grain
- amylopectin
- endosperm
-
pyrophosphorylase
- maize
- wheat
- potato
-
waxy
- glucans
- japonica
-
debranching
- amyloplasts
- triticum
- aestivum
- indica
- agpase
- kernel
-
chain-length
- isoamylase
- adpglucose
- sbeiib
-
starch-branching
-
homoeologous
-
starch-binding
- alpha-glucans
-
2.7.7.27
-
diphosphate-glucose
- pullulanase
-
high-amylose
-
hexaploid
- adp-glc
-
amylose-free
-
spikelet
-
grain-filling
- biofuel production
- food industry
- nutrition
- agriculture
-
chalky
The taxonomic range for the selected organisms is: Oryza sativa
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
Reaction Schemes
Synonyms
starch synthase, ssiia, gsase, ssiii, granule-bound starch synthase i, ssiiia, starch synthase iia, starch synthetase, starch synthase iii, starch synthase ii, 
more
topSYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
adenosine diphosphate glucose-starch glucosyltransferase
-
-
-
-
adenosine diphosphoglucose-starch glucosyltransferase
-
-
-
-
ADP-glucose starch synthase
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-
-
-
ADP-glucose synthase
-
-
-
-
ADP-glucose transglucosylase
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-
-
-
ADP-glucose-starch glucosyltransferase
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-
-
-
ADPG starch synthetase
-
-
-
-
ADPG-starch glucosyltransferase
-
-
-
-
GBSSI
glucosyltransferase, adenosine diphosphoglucose-starch
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-
-
-
SSI
SSIIa
SSIIIa
starch synthase I
starch synthetase
-
-
-
-
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
hexosyl group transfer
-
-
-
-
PATHWAY SOURCE
PATHWAYS
BRENDA
-
-, -
SYSTEMATIC NAME
IUBMB Comments
ADP-glucose:(1->4)-alpha-D-glucan 4-alpha-D-glucosyltransferase
The accepted name varies according to the source of the enzyme and the nature of its synthetic product, e.g. starch synthase, bacterial glycogen synthase. Similar to EC 2.4.1.11 [glycogen(starch) synthase] but the preferred or mandatory nucleoside diphosphate sugar substrate is ADP-alpha-D-glucose. The entry covers starch and glycogen synthases utilizing ADP-alpha-D-glucose.
CAS REGISTRY NUMBER
COMMENTARY
9030-10-8
-
SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
granule-bound starch synthase I is responsible for biosynthesis of extra-long unit chains of amylopectin in rice
-
-
?
ADP-alpha-D-glucose + [(1->4)-alpha-D-glucosyl]n
ADP + [(1->4)-alpha-D-glucosyl]n+1
-
-
-
-
?
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
granule-bound starch synthase I is responsible for biosynthesis of extra-long unit chains of amylopectin in rice
-
-
?
ADP-glucose + (1,4-alpha-glucosyl)n
ADP + (1,4-alpha-glucosyl)n+1
-
amylopectin chains are synthesized by the coordinated actions of SSI, SSIIa, and SSIIIa isoforms
-
-
?
ADP-glucose + (1,4-alpha-glucosyl)n
ADP + (1,4-alpha-glucosyl)n+1
-
SSI regulates the population of short chains. Low activity of SSI gives rise to the decrease of short chains in amylopectin of indica rice varieties, suggesting that SSI effects the differences in physicochemical properties between the varieties
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-
?
additional information
?
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-
a defect in starch synthase IIa causes that short A-chains can not reach a sufficient length for branching enzymes to act on them to produce B1-chains
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-
?
additional information
?
-
-
amylose in rice leaves is synthesized by OsGBSSII. Two independent pathways may be involved in OsGBSSII expression: sugar-regulating pathway, which is glycolysis-dependent, and an endogenous circadian rhythm-regulated pathway. N-starvation-induced OsGBSSII expression may depend on the sugar-regulating pathway
-
-
?
additional information
?
-
-
the activity of starch synthase IIa determines the type of amylopectin structure of rice starch to be either the typical indica-type or japonica-type, by playing a specific role in the synthesis of the long B1 chains by elongating short A and B1 chains, notwithstanding the presence of functional two additional SSII genes, a single SSI gene, two SSIII genes, and two SSIV genes in the rice plants. Val737 and Leu781 are essential not only for the optimal SSII1 activity, but also for the capacity to synthesize indica-type amylopectin
-
-
?
additional information
?
-
-
isoform SSI cannot compensate for the function of isoform SSIIa and elongation of DP higher 30 by isoform SSIIIa
-
-
-
additional information
?
-
-
isoform SSIIa preferentially elongates outer but not inner chains of amylopectin. Isoform SSIIa can complement most isoform SSI functions that use glucan chains with DP 6-7 to generate DP 8-12 chains but cannot fully compensate for the elongation of DP 16-19 chains. Isoform SSIIa cannot compensate for elongation of DP higher 30 by isoform SSIIIa
-
-
-
additional information
?
-
-
isoform SSIIIa cannot compensate for the function of isoform SSIIa
-
-
-
NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
granule-bound starch synthase I is responsible for biosynthesis of extra-long unit chains of amylopectin in rice
-
-
?
ADP-alpha-D-glucose + [(1->4)-alpha-D-glucosyl]n
ADP + [(1->4)-alpha-D-glucosyl]n+1
-
-
-
-
?
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
granule-bound starch synthase I is responsible for biosynthesis of extra-long unit chains of amylopectin in rice
-
-
?
ADP-glucose + (1,4-alpha-glucosyl)n
ADP + (1,4-alpha-glucosyl)n+1
-
amylopectin chains are synthesized by the coordinated actions of SSI, SSIIa, and SSIIIa isoforms
-
-
?
ADP-glucose + (1,4-alpha-glucosyl)n
ADP + (1,4-alpha-glucosyl)n+1
-
SSI regulates the population of short chains. Low activity of SSI gives rise to the decrease of short chains in amylopectin of indica rice varieties, suggesting that SSI effects the differences in physicochemical properties between the varieties
-
-
?
additional information
?
-
-
a defect in starch synthase IIa causes that short A-chains can not reach a sufficient length for branching enzymes to act on them to produce B1-chains
-
-
?
additional information
?
-
-
amylose in rice leaves is synthesized by OsGBSSII. Two independent pathways may be involved in OsGBSSII expression: sugar-regulating pathway, which is glycolysis-dependent, and an endogenous circadian rhythm-regulated pathway. N-starvation-induced OsGBSSII expression may depend on the sugar-regulating pathway
-
-
?
additional information
?
-
-
the activity of starch synthase IIa determines the type of amylopectin structure of rice starch to be either the typical indica-type or japonica-type, by playing a specific role in the synthesis of the long B1 chains by elongating short A and B1 chains, notwithstanding the presence of functional two additional SSII genes, a single SSI gene, two SSIII genes, and two SSIV genes in the rice plants. Val737 and Leu781 are essential not only for the optimal SSII1 activity, but also for the capacity to synthesize indica-type amylopectin
-
-
?
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
citrate
-
isoform SSI and SSIIa are 3.4 and 4.4fold activated by 0.3 M citrate, respectively
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
-
SSIIa protein is present even in Nipponbare endosperm but is not associated with starch granules at the milky stage of endosperm
-
the SSI activity of an indica rice variety, Kasalath, is significantly lower than that of a japonica rice variety, Nipponbare. The low activity in Kasalath is maintained during seed development The low expression of SSI in Kasalath is controlled at the transcription levels of SSI mRNA
-
the content of amylose in SA418 grain is higher than Tainung 67 and SA419 grains throughout the entire grain filling period, possibly due to its superiority to synthesize amylose through GBSS
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
malfunction
metabolism
-
granule bound starch synthase I is the dominant enzyme controlling long amylose chain synthesis. The enzyme plays a key role in determining the amylose content of cereal grains, and it competes with starch branching enzyme I during starch biosynthesis
physiological function
malfunction
-
starch synthase I deficiency also affects the extent of binding of other isozymes to starch granules
malfunction
-
mutations in the starch synthase IIIa gene, in combination with a highly expressed Waxy gene, lead to a high level of resistant starch
physiological function
-
construction of double mutants defective in isoforms SSI and SSIIIa. In the F2 generation, two opaque seed types were found to have either the ss1ss1/SS3ass3a or the SS1ss1/ss3ass3a genotype. The endosperm of the two types of opaque seeds displays lower starch synthase activity and contains the unique starch with modified fine structure, round-shaped starch granules, high amylose content, and specific physicochemical properties. The seed weight is about 90% of that of the wild type. The amount of granule-bound starch synthase I and the activity of ADP-glucose diphosphorylase are higher than in the wild type and parent mutant lines. The double-recessive homozygous mutant prepared from both ss1 and ss3a null mutants is considered sterile, while the mutant produced by the leaky ss1 mutant with the ss3a null mutant is fertile
physiological function
-
grain qualities and physicochemical properties of starch are determined by SSIIIa. Biosynthesis of resistant starch is regulated by SSIIIa. Mutation of SSIIIa gene results in elevation of resistant starch
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
12000
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
oligomer
-
enzyme is active in at least 2 oligomeric forms, bands in SDS-PAGE of 11500 Da, 20000 Da, 35000 Da, 50000 Da, 68000 Da, and in gel filtration of 22000 Da and 67000 Da
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
glycoprotein
-
glycogen synthase II, 1.7% carbohydrate may be due to an endogenous primer
STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
cloning and sequencing of cDNA encoding SSIIa of japonica and indica rice cultivars, expression in Escherichia coli
-
APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
food industry
-
resistant starch (RS) has the potential to protect against diabetes and reduce the incidence of diarrhea, inflammatory bowel disease, colon cancer, and chronic renal and hepatic diseases. Soluble starch synthase SSIIIa has a critical role in synthesizing resistant starch in rice
nutrition
-
analysis of the natural variations of isoforms granule-bound starch synthase GBSSI, starch synthases SSI and SSIIa and their effect on starch properties and eating quality of rice. Rice with the combinantion of the Wx allele for GBSSI and the alk allele for SSIIa has soft and sticky texture both after cooking and after storage. Variation of SSI alleles hardly affects the eating quality
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Taira, T.; Uematsu, M.; Nakano, Y.; Morikawa, T.
Molecular identification and comparison of the starch synthase bound to starch granules between endosperm and leaf blades in rice plants
Biochem. Genet.
29
301-311
1991
Oryza sativa
Pisigan, R.A.; del Rosario, E.J.
Isoenzymes of soluble starch synthase from Oryza sativa grains
Phytochemistry
15
71-73
1976
Oryza sativa
-
Antonio, A.A.; del Rosario, E.J.; Juliano, B.
Molecular weight of starch synthetase from Oryza sativa leaves
Phytochemistry
12
1929-1932
1973
Oryza sativa
-
Umemoto, T.; Aoki, N.; Lin, H.; Nakamura, Y.; Inouchi, N.; Sato, Y.; Yano, M.; Hirabayashi, H.; Maruyama, S.
Natural variation in rice starch synthase IIa affects enzyme and starch properties
Funct. Plant Biol.
31
671-684
2004
Oryza sativa
Nakamura, Y.; Francisco, P.B., Jr.; Hosaka, Y.; Sato, A.; Sawada, T.; Kubo, A.; Fujita, N.
Essential amino acids of starch synthase IIa differentiate amylopectin structure and starch quality between japonica and indica rice varieties
Plant Mol. Biol.
58
213-227
2005
Oryza sativa
Dian, W.; Jiang, H.; Chen, Q.; Liu, F.; Wu, P.
Cloning and characterization of the granule-bound starch synthase II gene in rice: gene expression is regulated by the nitrogen level, sugar and circadian rhythm
Planta
218
261-268
2003
Oryza sativa
Takemoto-Kuno, Y.; Suzuki, K.; Nakamura, S.; Satoh, H.; Ohtsubo, K.
Soluble starch synthase I effects differences in amylopectin structure between indica and japonica rice varieties
J. Agric. Food Chem.
54
9234-9240
2006
Oryza sativa
Dian, W.; Jiang, H.; Wu, P.
Evolution and expression analysis of starch synthase III and IV in rice
J. Exp. Bot.
56
623-632
2005
Oryza sativa (Q6UBQ7), Oryza sativa (Q84VC7), Oryza sativa (Q8L8G9), Oryza sativa (Q8W1P1), Oryza sativa
Fujita, N.; Yoshida, M.; Asakura, N.; Ohdan, T.; Miyao, A.; Hirochika, H.; Nakamura, Y.
Function and characterization of starch synthase I using mutants in rice
Plant Physiol.
140
1070-1084
2006
Oryza sativa
Jeng, T.L.; Wang, C.S.; Tseng, T.H.; Sung, J.M.
Expression of granule-bound starch synthase in developing rice grain
J. Sci. Food Agric.
87
2456-2463
2007
Oryza sativa
Hanashiro, I.; Itoh, K.; Kuratomi, Y.; Yamazaki, M.; Igarashi, T.; Matsugasako, J.; Takeda, Y.
Granule-bound starch synthase I is responsible for biosynthesis of extra-long unit chains of amylopectin in rice
Plant Cell Physiol.
49
925-933
2008
Oryza rufipogon, Oryza sativa (B1B5Z0), Oryza sativa (B1B5Z1), Oryza sativa
Umemoto, T.; Horibata, T.; Aoki, N.; Hiratsuka, M.; Yano, M.; Inouchi, N.
Effects of variations in starch synthase on starch properties and eating quality of rice
Plant Prod. Sci.
11
472-480
2008
Oryza sativa
-
Fujita, N.; Satoh, R.; Hayashi, A.; Kodama, M.; Itoh, R.; Aihara, S.; Nakamura, Y.
Starch biosynthesis in rice endosperm requires the presence of either starch synthase I or IIIa
J. Exp. Bot.
62
4819-4831
2011
Oryza sativa
Abe, N.; Asai, H.; Yago, H.; Oitome, N.F.; Itoh, R.; Crofts, N.; Nakamura, Y.; Fujita, N.
Relationships between starch synthase I and branching enzyme isozymes determined using double mutant rice lines
BMC Plant Biol.
14
80
2014
Oryza sativa
Nakamura, Y.; Aihara, S.; Crofts, N.; Sawada, T.; Fujita, N.
In vitro studies of enzymatic properties of starch synthases and interactions between starch synthase I and starch branching enzymes from rice
Plant Sci.
224
1-8
2014
Oryza sativa
Crofts, N.; Sugimoto, K.; Oitome, N.F.; Nakamura, Y.; Fujita, N.
Differences in specificity and compensatory functions among three major starch synthases determine the structure of amylopectin in rice endosperm
Plant Mol. Biol.
94
399-417
2017
Oryza sativa
Mishra, B.P.; Kumar, R.; Mohan, A.; Gill, K.S.
Conservation and divergence of starch synthase III genes of monocots and dicots
PLoS ONE
12
e0189303
2017
Arabidopsis thaliana, Brachypodium distachyon, Glycine max, Hordeum vulgare, Oryza sativa, Sorghum bicolor, Zea mays
Zhou, H.; Wang, L.; Liu, G.; Meng, X.; Jing, Y.; Shu, X.; Kong, X.; Sun, J.; Yu, H.; Smith, S.M.; Wu, D.; Li, J.
Critical roles of soluble starch synthase SSIIIa and granule-bound starch synthase Waxy in synthesizing resistant starch in rice
Proc. Natl. Acad. Sci. USA
113
12844-12849
2016
Oryza sativa
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