EC Number   |
Substrates |
Organism |
Products  |
Reversibility |
|---|
    2.4.1.21 | methyl-6'-alpha-maltosyl-alpha-maltotrioside + ADP-glucose |
SSII catalyses an equimolar and non-processive elongation reaction of this substrate. Both of the non-reducing ends of methyl 6'-alpha-maltosyl-6'-maltotrioside are extended equally resulting in two hexasaccharide products in nearly equal amounts |
Pisum sativum |
? |
- |
? |
| 2.4.1.21 | more |
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 |
Oryza sativa |
? |
- |
? |
| 2.4.1.21 | more |
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 |
Oryza sativa |
? |
- |
? |
| 2.4.1.21 | more |
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 |
Oryza sativa |
? |
- |
? |
| 2.4.1.21 | more |
the starch synthase isoenzymes PvSSI and PvSSII-1 are responsible for synthesis of transistory starch and for the synthesis of storage starch in early developing seeds |
Phaseolus vulgaris |
? |
- |
? |
| 2.4.1.21 | more |
amylose-free transgenic sweet potato plants are produced by inhibiting sweet potato GBSSI gene expression through RNA interference |
Ipomoea batatas |
? |
- |
? |
| 2.4.1.21 | more |
the barley shrunken grain mutant M292 has a novel high-amylose starch phenotype caused by a mutation in the starch synthase IIa gene (SsIIa) located at the starch excess-6 (sex6) locus on chromosome 7H of barley. The loss of SSIIa enzyme activity leads to a decrease in amylopectin synthesis to less than 20% of the levels found in wild-type grains |
Hordeum vulgare |
? |
- |
? |
| 2.4.1.21 | more |
potato starch-synthase synthesizes alpha-(1-4)-linked amylose chains de novo without the need of a primer. D-Glucopyranosyl and D-glucanyl starch chains are covalently attached to the active-site of starch synthase during catalysis. D-Glucose is added to the reducing-end of the growing chain processively, suggesting a two catalytic-site insertion mechanism |
Solanum tuberosum |
? |
- |
? |
| 2.4.1.21 | more |
less than 1% activity with D-glucose |
Arabidopsis thaliana |
? |
- |
? |
| 2.4.1.21 | more |
no activity with maltohexaose |
Oryza sativa |
? |
- |
? |
