Pathway · 3 proteins
Starch and sucrose metabolism
Proteins of this group that KEGG places on its “Starch and sucrose metabolism” map for Aquifex aeolicus.
How it works
This map covers the building and use of glucose stores. The three proteins here build glycogen: glycogen synthase adds glucose units, the branching enzyme adds branches, and 4-alpha-glucanotransferase reshapes the chains.
Grouped by KEGG pathway map. The explanation above is the atlas’s own; the map itself covers more organisms than Aquifex.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Glycogen synthase | 2.4.1.21 | [(1->4)-alpha-D-glucosyl](n) + ADP-alpha-D-glucose = [(1->4)-alpha-D-glucosyl](n+1) + ADP + H(+) | ADP-alpha-D-glucose | 463 | Unspecified |
| 1,4-alpha-glucan branching enzyme GlgB | 2.4.1.18 | Transfers a segment of a (1->4)-alpha-D-glucan chain to a primary hydroxy group in a similar glucan chain. | — | 630 | Unspecified |
| 4-alpha-glucanotransferase | 2.4.1.25 | Transfers a segment of a (1->4)-alpha-D-glucan to a new position in an acceptor, which may be glucose or a (1->4)-alpha-D-glucan. | — | 485 | Unspecified |
Also part of this pathway
These proteins are described under another pathway, but also take part here.
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| UTP--glucose-1-phosphate uridylyltransferaseHome: Amino sugar and nucleotide sugar metabolism | 2.7.7.9 | alpha-D-glucose 1-phosphate + UTP + H(+) = UDP-alpha-D-glucose + diphosphate | — | 297 | Step named |
| Bifunctional phosphoglucose/phosphomannose isomeraseHome: Glycolysis / Gluconeogenesis | 5.3.1.8; 5.3.1.9 | alpha-D-glucose 6-phosphate = beta-D-fructose 6-phosphate | D-fructose 6-phosphate | 320 | Step named |
| Glycogen phosphorylaseHome: Not yet placed in a pathway | 2.4.1.1 | [(1->4)-alpha-D-glucosyl](n) + phosphate = [(1->4)-alpha-D-glucosyl](n-1) + alpha-D-glucose 1-phosphate | — | 692 | Step named |
Origins
How could a cell store sugar for later before these enzymes existed?
None of the books searched discusses the origin of sugar storage.
Storing glucose as glycogen takes an enzyme to build chains, one to branch them and one to reshape them, and stored sugar is useful only if the cell can also break it down when needed. Three proteins in this pathway serve storage.
The wider question for this part of the cell: origins for conserved, but we cannot say what they do.
Sources
- KEGG map aae00500 (enzymes of this organism highlighted)
Other pathways in this group: tRNA charging · Nutrient and metabolic state · Biosynthesis of various nucleotide sugars · Purine metabolism · Bacterial secretion system · Glyoxylate and dicarboxylate metabolism · Homologous recombination · Fructose and mannose metabolism · Streptomycin biosynthesis · Other carbon fixation pathways · Nicotinate and nicotinamide metabolism · Not yet placed in a pathway