Abstract
Extracts of Brassica napus (oilseed rape) seeds contain type 1 and type 2A protein phosphatases whose properties are indistinguishable from the corresponding enzymes in mammalian tissues. The type 1 activity dephosphorylated the beta-subunit of phosphorylase kinase selectively and was inhibited by the same concentrations of okadaic acid [IC50 (concentration causing 50% inhibition) approximately 10 nM], mammalian inhibitor 1 (IC50 = 0.6 nM) and mammalian inhibitor 2 (IC50 = 2.0 nM) as the rabbit muscle type 1 phosphatase. The plant type 2A activity dephosphorylated the alpha-subunit of phosphorylase kinase preferentially, was exquisitely sensitive to okadaic acid (IC50 approximately 0.1 nM), and was unaffected by inhibitors 1 and 2. As in mammalian tissues, a substantial proportion of plant type 1 phosphatase activity (40%) was particulate, whereas plant type 2A phosphatase was cytosolic. The specific activities of the plant type 1 and type 2A phosphatases were as high as in mammalian tissue extracts, but no type 2B or type 2C phosphatase activity was detected. The results demonstrate that the improved procedure for identifying and quantifying protein phosphatases in animal cells is applicable to higher plants, and suggests that okadaic acid may provide a new method for identifying plant enzymes that are regulated by reversible phosphorylation.
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Claims 14
Claim · model-written summary
Oilseed rape seeds contain type 1 and type 2A phosphatases with properties indistinguishable from mammalian counterparts.
- Taxon
- Brassica napus
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napuse0 - Organ / stage
- seedse0
- Gene
- type 1 and type 2A protein phosphatasese0
- Outcome
- properties are indistinguishablee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
e0“Extracts of Brassica napus (oilseed rape) seeds contain type 1 and type 2A protein phosphatases whose properties are indistinguishable from the corresponding enzymes in mammalian tissues.”
Claim · model-written summary
Plant type 1 activity selectively dephosphorylated the beta-subunit of phosphorylase kinase.
- Taxon
- higher plantsEmbryophytat0
- Gene
- type 1e0
- Outcome
- dephosphorylated the beta-subunit of phosphorylase kinase selectivelye0
Verbatim
e0“The type 1 activity dephosphorylated the beta-subunit of phosphorylase kinase selectively”
t0“higher plants”
Claim · model-written summary
Okadaic acid inhibited type 1 activity with an approximate IC50 of 10 nM.
- Taxon
- higher plantsEmbryophytat0
- Treatment
- okadaic acide0
- Gene
- type 1t0
- Outcome
- inhibitede0
- Direction
- inhibitede0
- Value
- approximately 10 nMe0
Not reportedComparator
Verbatim
e0“was inhibited by the same concentrations of okadaic acid [IC50 (concentration causing 50% inhibition) approximately 10 nM]”
t0“type 1 and type 2A protein phosphatases in higher plants”
Claim · model-written summary
Mammalian inhibitor 1 inhibited plant type 1 activity with IC50 0.6 nM.
- Taxon
- higher plantsEmbryophytat0
- Treatment
- mammalian inhibitor 1e0
- Outcome
- IC50e0
- Value
- 0.6 nMe0
Not reportedComparatorDirection
Verbatim
e0“mammalian inhibitor 1 (IC50 = 0.6 nM)”
t0“higher plants”
Claim · model-written summary
Mammalian inhibitor 2 inhibited plant type 1 activity with IC50 2.0 nM.
- Taxon
- higher plantsEmbryophytat0
- Treatment
- mammalian inhibitor 2e0
- Outcome
- IC50e0
- Value
- 2.0 nMe0
Not reportedComparatorDirection
Verbatim
e0“mammalian inhibitor 2 (IC50 = 2.0 nM)”
t0“higher plants”
Claim · model-written summary
Plant type 2A preferentially dephosphorylated the alpha-subunit of phosphorylase kinase.
- Taxon
- higher plantsEmbryophytat0
- Gene
- type 2Ae0
- Outcome
- dephosphorylated the alpha-subunit of phosphorylase kinase preferentiallye0
Verbatim
e0“The plant type 2A activity dephosphorylated the alpha-subunit of phosphorylase kinase preferentially”
t0“higher plants”
Claim · model-written summary
Plant type 2A was sensitive to okadaic acid at approximately 0.1 nM IC50.
- Taxon
- higher plantsEmbryophytat0
- Treatment
- okadaic acide0
- Outcome
- sensitivee0
- Direction
- sensitivee0
- Value
- approximately 0.1 nMe0
Not reportedComparator
Verbatim
e0“was exquisitely sensitive to okadaic acid (IC50 approximately 0.1 nM)”
t0“higher plants”
Claim · model-written summary
Inhibitors 1 and 2 did not affect plant type 2A activity.
- Taxon
- higher plantsEmbryophytat0
- Treatment
- inhibitors 1 and 2e0
- Outcome
- unaffectede0
- Direction
- unaffectede0
Not reportedComparator
Verbatim
e0“was unaffected by inhibitors 1 and 2.”
t0“higher plants”
Claim · model-written summary
Forty percent of plant type 1 activity was particulate.
- Taxon
- higher plantsEmbryophytat0
- Gene
- type 1 phosphatasee0
- Outcome
- was particulatee0
- Value
- 40%e0
Verbatim
e0“a substantial proportion of plant type 1 phosphatase activity (40%) was particulate”
t0“higher plants”
Claim · model-written summary
Plant type 2A phosphatase was cytosolic.
- Taxon
- higher plantsEmbryophytat0
- Gene
- type 2A phosphatasee0
- Outcome
- was cytosolice0
Verbatim
e0“plant type 2A phosphatase was cytosolic”
t0“higher plants”
Claim · model-written summary
Plant type 1 and 2A specific activities were as high as in mammalian extracts.
Verbatim
e0“The specific activities of the plant type 1 and type 2A phosphatases were as high as in mammalian tissue extracts”
t0“higher plants”
Claim · model-written summary
No type 2B or type 2C activity was detected.
- Taxon
- higher plantsEmbryophytat0
- Gene
- type 2B or type 2C phosphatasee0
- Outcome
- no type 2B or type 2C phosphatase activity was detectede0
Not reportedDirection
Verbatim
e0“no type 2B or type 2C phosphatase activity was detected”
t0“higher plants”
Claim · model-written summary
The animal-cell phosphatase identification and quantification procedure was applicable to higher plants.
- Taxon
- higher plantsEmbryophytae0
- Outcome
- is applicable to higher plantse0
- Comparator
- animal cellse0
Verbatim
e0“the improved procedure for identifying and quantifying protein phosphatases in animal cells is applicable to higher plants”
Claim · model-written summary
The authors suggest okadaic acid may identify plant enzymes regulated by reversible phosphorylation.
- Taxon
- plante0
- Treatment
- okadaic acide0
- Outcome
- identifying plant enzymes that are regulated by reversible phosphorylatione0
Not reportedComparatorValue
Verbatim
e0“okadaic acid may provide a new method for identifying plant enzymes that are regulated by reversible phosphorylation”