9lfn

Structural highlights

Function

ISOA1_ORYSJ Starch-debranching enzyme involved in amylopectin biosynthesis in endosperm. Functions by removing excess branches or improper branches that interfere with the formation of double helices of the cluster chains of amylopectin and crystallization of starch (PubMed:10517831, PubMed:15618430, PubMed:16953433, PubMed:21436381). Works as ISA1 homooligomer or together with ISA2 as heterooligomer. The heterooligomer ISA1 and ISA2 possesses higher affinity than the ISA1 homooligomer for various branched polyglucans in vitro, but no marked differences exist in chain preferences for debranching of amylopectin and phytoglycogen between these forms (PubMed:16953433, PubMed:21436381).^{[1] [2] [3] [4]}

References

1. ↑ Kubo A, Fujita N, Harada K, Matsuda T, Satoh H, Nakamura Y. The starch-debranching enzymes isoamylase and pullulanase are both involved in amylopectin biosynthesis in rice endosperm Plant Physiol. 1999 Oct;121(2):399-410. PMID:10517831
2. ↑ Kubo A, Rahman S, Utsumi Y, Li Z, Mukai Y, Yamamoto M, Ugaki M, Harada K, Satoh H, Konik-Rose C, Morell M, Nakamura Y. Complementation of sugary-1 phenotype in rice endosperm with the wheat isoamylase1 gene supports a direct role for isoamylase1 in amylopectin biosynthesis. Plant Physiol. 2005 Jan;137(1):43-56. PMID:15618430 doi:10.1104/pp.104.051359
3. ↑ Utsumi Y, Nakamura Y. Structural and enzymatic characterization of the isoamylase1 homo-oligomer and the isoamylase1-isoamylase2 hetero-oligomer from rice endosperm. Planta. 2006 Dec;225(1):75-87. PMID:16953433 doi:10.1007/s00425-006-0331-z
4. ↑ Utsumi Y, Utsumi C, Sawada T, Fujita N, Nakamura Y. Functional diversity of isoamylase oligomers: the ISA1 homo-oligomer is essential for amylopectin biosynthesis in rice endosperm. Plant Physiol. 2011 May;156(1):61-77. PMID:21436381 doi:10.1104/pp.111.173435