This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: starch mobilization from cereal endosperm, starch degradation from cereal endosperm
|Superclasses:||Biosynthesis → Carbohydrates Biosynthesis → Sugars Biosynthesis|
|Degradation/Utilization/Assimilation → Carbohydrates Degradation → Polysaccharides Degradation → Starch Degradation|
|Degradation/Utilization/Assimilation → Polymeric Compounds Degradation → Polysaccharides Degradation → Starch Degradation|
Expected Taxonomic Range: Poaceae
Plants accumulate and mobilize starch in both photosynthetic tissue (leaves) and non-photosynthetic storage tissues (such as tuber and seed endosperm). In leaves, starch is synthesized during the light period and is degraded during the dark period. In storage tissues, starch is degraded during tuber sprouting and seed germinating. Except for seed endosperm where starch degradation occurs in an acellular tissue, starch degradation generally occurs in the plastids (chloroplast of leaves and amyloplast of tubers) where starch accumulates. Isoforms of the starch degradation enzymes are also found and in many cases abundant in extra-plastidic subcellular locations in leaves and tubers. Their physiological functions are not well understood [Zeeman10].
About This Pathway
This pathway represents the starch degradation route present in the endosperm of cereal crops. Many details of the pathway as well as the relative importance of the four types of enzymes that contribute to this process, namely α-amylases, β-amylases, limit dextran debranching enzymes, and α-glucosidases, are still the subject of investigation and debate [Zeeman10, Stanley11].
Unification Links: PlantCyc:PWY-842
Finnie11: Finnie C, Andersen B, Shahpiri A, Svensson B (2011). "Proteomes of the barley aleurone layer: A model system for plant signalling and protein secretion." Proteomics 11(9);1595-605. PMID: 21433287
Rejzek11: Rejzek M, Stevenson CE, Southard AM, Stanley D, Denyer K, Smith AM, Naldrett MJ, Lawson DM, Field RA (2011). "Chemical genetics and cereal starch metabolism: structural basis of the non-covalent and covalent inhibition of barley β-amylase." Mol Biosyst 7(3);718-30. PMID: 21085740
Stanley11: Stanley D, Rejzek M, Naested H, Smedley M, Otero S, Fahy B, Thorpe F, Nash RJ, Harwood W, Svensson B, Denyer K, Field RA, Smith AM (2011). "The role of alpha-glucosidase in germinating barley grains." Plant Physiol 155(2);932-43. PMID: 21098673
Sun91: Sun ZT, Henson CA (1991). "A quantitative assessment of the importance of barley seed alpha-amylase, beta-amylase, debranching enzyme, and alpha-glucosidase in starch degradation." Arch Biochem Biophys 284(2);298-305. PMID: 1824915
Wu02c: Wu C, Colleoni C, Myers AM, James MG (2002). "Enzymatic properties and regulation of ZPU1, the maize pullulanase-type starch debranching enzyme." Arch Biochem Biophys 406(1);21-32. PMID: 12234486
Dinges03: Dinges JR, Colleoni C, James MG, Myers AM (2003). "Mutational analysis of the pullulanase-type debranching enzyme of maize indicates multiple functions in starch metabolism." Plant Cell 2003;15(3);666-80. PMID: 12615940
Dong97: Dong G, Vieille C, Zeikus JG (1997). "Cloning, sequencing, and expression of the gene encoding amylopullulanase from Pyrococcus furiosus and biochemical characterization of the recombinant enzyme." Appl Environ Microbiol 63(9);3577-84. PMID: 9293009
Frandsen00: Frandsen TP, Lok F, Mirgorodskaya E, Roepstorff P, Svensson B (2000). "Purification, enzymatic characterization, and nucleotide sequence of a high-isoelectric-point alpha-glucosidase from barley malt." Plant Physiol 123(1);275-86. PMID: 10806244
Fulton08: Fulton DC, Stettler M, Mettler T, Vaughan CK, Li J, Francisco P, Gil M, Reinhold H, Eicke S, Messerli G, Dorken G, Halliday K, Smith AM, Smith SM, Zeeman SC (2008). "Beta-AMYLASE4, a noncatalytic protein required for starch breakdown, acts upstream of three active beta-amylases in Arabidopsis chloroplasts." Plant Cell 20(4);1040-58. PMID: 18390594
Naested06: Naested H, Kramhoft B, Lok F, Bojsen K, Yu S, Svensson B (2006). "Production of enzymatically active recombinant full-length barley high pI alpha-glucosidase of glycoside family 31 by high cell-density fermentation of Pichia pastoris and affinity purification." Protein Expr Purif 46(1);56-63. PMID: 16343940
Vinje10: Vinje MA, Duke SH, Henson CA (2010). "Utilization of Different Bmy1 Intron III Alleles for Predicting β-Amylase Activity and Thermostability in Wild and Cultivated Barley." Plant Molecular Biology Reporter 28(3);491-501.
Vinje11: Vinje MA, Willis DK, Duke SH, Henson CA (2011). "Differential RNA expression of Bmy1 during barley seed development and the association with β-amylase accumulation, activity, and total protein." Plant Physiol Biochem 49(1);39-45. PMID: 20974538
Yoshigi94a: Yoshigi N, Okada Y, Sahara H, Koshino S (1994). "Expression in Escherichia coli of cDNA encoding barley beta-amylase and properties of recombinant beta-amylase." Biosci Biotechnol Biochem 58(6);1080-6. PMID: 7765034
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