EC Number   |
General Information |
Reference |
|---|
    3.2.1.68 | evolution |
subunit ISA1 is a family 13 glycoside hydrolase, which has activity for hydrolyzing alpha-1,6-glucosidic linkages corresponding to branch points of growing amylopectin molecules |
-, 732146 |
| 3.2.1.68 | evolution |
subunit ISA2 is a family 13 glycoside hydrolase, but its putative catalytic residues are altered, rendering it enzymatically inactive. Despite its inactivity, ISA2 is evolutionarily conserved in plants, and has been suggested to play a role as a regulatory subunit for ISA1 |
-, 732146 |
| 3.2.1.68 | evolution |
the enzyme belongs to the glycosyl hydrolase family 13 GH13, and harbors a carbohydrate-binding module family 48 (CBM48) domain |
732581, 732655 |
| 3.2.1.68 | evolution |
the enzyme harbors a carbohydrate-binding module family 48 (CBM48) domain |
-, 732278 |
| 3.2.1.68 | malfunction |
both overexpression and loss of function of isoamylase 3 in the endosperm generated pleomorphic amyloplasts and starch granules |
716495 |
| 3.2.1.68 | malfunction |
loss of isozyme ISA1 or ISA2 causes phytoglycogen accumulation |
732750 |
| 3.2.1.68 | malfunction |
mutants of the STA8 locus accumulate both phytoglycogen and a reduced amount of high amylose starch |
-, 732146 |
| 3.2.1.68 | malfunction |
mutation of the STA7 locus leads to a very severe reduction of starch content and its replacement by a water-soluble polysaccharide phytoglycogen |
-, 732146 |
| 3.2.1.68 | malfunction |
seeds of the homozygous mutants, cr-isa1-1 (type 1, with an adenine insertion) and cr-isa1-2 (type 3, with a cytosine deletion) display a shrunken endosperm with significantly lower grain weight. Abnormal starch granules and amyloplasts are found in cr-isa1-1 and cr-isa1-2 endosperm cells. The contents of total starch, amylose and amylopectin in the endosperm of the cr-isa1 mutants are significantly reduced, whereas sugar content and starch gel consistency were observably increased compared to the wild type. The gelatinization temperature and starch chain length distributions of the cr-isa1 mutants are also altered. The transcript levels of most starch synthesis-related genes are significantly lower in cr-isa1 mutants |
752159 |
| 3.2.1.68 | malfunction |
the ISA1 homomer does not provide the full physiological function of ISA activity in maize leaves. This is in contrast to the endosperm, where loss of ISA2, and thus the ISA1/ISA2 heteromeric enzyme, can be tolerated without major defects. Mutants without ISA2 differ in leaf starch content, granule morphology, and amylopectin structure compared with nonmutants or lines lacking both ISA1 and ISA2, mutant phenotypes, overview |
732581 |
