Abstract
The cytokinin receptor AHK3 of Arabidopsis thaliana plays a predominant role in shoot development. A study of the hormone-binding characteristics of AHK3 compared with the mainly root-confined receptor CRE1/AHK4 has been accomplished using a live-cell binding assay on transgenic bacteria expressing individual receptor proteins. Both receptors bound trans-zeatin (tZ) with high affinity. Scatchard analysis showed a linear function corresponding to an apparent K(D) of 1-2 nM for the AHK3 receptor-hormone complex, which is close to the K(D) (2-4 nM) for the CRE1/AHK4 receptor-hormone complex. The specific binding of tZ to both receptors was pH dependent, AHK3 being more sensitive to pH changes than CRE1/AHK4. Hormone binding was reversible, at least for the bulk of (3)H-zeatin, and influenced by monovalent cations, while divalent cations (Ca(2+), Mg(2+), Mn(2+)) at physiological concentrations had no significant effect. AHK3 differed significantly from CRE1/AHK4 in relative affinity to some cytokinins. AHK3 had an approximately 10-fold lower affinity to isopentenyladenine (iP) and its riboside, but a higher affinity to dihydrozeatin than CRE1/AHK4. For AHK3, cytokinin ribosides (tZR, iPR) and cis-zeatin had true binding activity, although lower than that of tZ. The phenylurea-derived cytokinin thidiazuron was a strong competitor and bound to the same site as did adenine-derived cytokinins. The inhibitor of cytokinin action butan-1-ol had little effect on cytokinin-receptor complex formation. The revealed properties of AHK3 suggest its specific function in root-to-shoot communication.
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Claims 15
Claim · model-written summary
Both AHK3 and CRE1/AHK4 bound trans-zeatin with high affinity.
- Taxon
- Arabidopsis
Arabidopsist0 - Compound
- trans-zeatin (tZ)e0
- Outcome
- bound trans-zeatin (tZ)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e0“Both receptors bound trans-zeatin (tZ) with high affinity”
Claim · model-written summary
The apparent K(D) of AHK3 for trans-zeatin was 1-2 nM, close to the 2-4 nM of CRE1/AHK4.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AHK3e1
- Outcome
- apparent K(D)e1
- Value
- 1-2 nMe1
- Qualifier
- 2-4 nMe1
- Comparator
- CRE1/AHK4e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e1“Scatchard analysis showed a linear function corresponding to an apparent K(D) of 1-2 nM for the AHK3 receptor-hormone complex, which is close to the K(D) (2-4 nM) for the CRE1/AHK4 receptor-hormone complex”
Claim · model-written summary
Specific binding of tZ to both receptors was pH dependent.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- pHe2
- Outcome
- specific binding of tZe2
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e2“The specific binding of tZ to both receptors was pH dependent, AHK3 being more sensitive to pH changes than CRE1/AHK4”
Claim · model-written summary
AHK3 was more sensitive to pH changes than CRE1/AHK4 in tZ binding.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- pH changese2
- Gene
- AHK3e2
- Outcome
- sensitive to pH changese2
- Direction
- more sensitivee2
- Comparator
- CRE1/AHK4e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e2“The specific binding of tZ to both receptors was pH dependent, AHK3 being more sensitive to pH changes than CRE1/AHK4”
Claim · model-written summary
Hormone binding was reversible for the bulk of 3H-zeatin.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- (3)H-zeatine3
- Outcome
- Hormone binding was reversiblee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e3“Hormone binding was reversible, at least for the bulk of (3)H-zeatin, and influenced by monovalent cations, while divalent cations (Ca(2+), Mg(2+), Mn(2+)) at physiological concentrations had no significant effect”
Claim · model-written summary
Monovalent cations influenced hormone binding.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- monovalent cationse3
- Outcome
- Hormone bindinge3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e3“Hormone binding was reversible, at least for the bulk of (3)H-zeatin, and influenced by monovalent cations, while divalent cations (Ca(2+), Mg(2+), Mn(2+)) at physiological concentrations had no significant effect”
Claim · model-written summary
Divalent cations at physiological concentrations had no significant effect on hormone binding.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- divalent cations (Ca(2+), Mg(2+), Mn(2+)) at physiological concentrationse3
- Outcome
- Hormone bindinge3
- Direction
- no significant effecte3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e3“Hormone binding was reversible, at least for the bulk of (3)H-zeatin, and influenced by monovalent cations, while divalent cations (Ca(2+), Mg(2+), Mn(2+)) at physiological concentrations had no significant effect”
Claim · model-written summary
AHK3 differed significantly from CRE1/AHK4 in relative affinity to some cytokinins.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AHK3e4
- Outcome
- relative affinity to some cytokininse4
- Comparator
- CRE1/AHK4e4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e4“AHK3 differed significantly from CRE1/AHK4 in relative affinity to some cytokinins”
Claim · model-written summary
AHK3 had an approximately 10-fold lower affinity to isopentenyladenine (iP) and its riboside than CRE1/AHK4.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AHK3e5
- Compound
- isopentenyladenine (iP)e5
- Outcome
- affinity to isopentenyladenine (iP) and its ribosidee5
- Direction
- lowere5
- Value
- approximately 10-folde5
- Comparator
- CRE1/AHK4e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e5“AHK3 had an approximately 10-fold lower affinity to isopentenyladenine (iP) and its riboside, but a higher affinity to dihydrozeatin than CRE1/AHK4”
Claim · model-written summary
AHK3 had a higher affinity to dihydrozeatin than CRE1/AHK4.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AHK3e5
- Compound
- dihydrozeatine5
- Outcome
- affinity to dihydrozeatine5
- Direction
- highere5
- Comparator
- CRE1/AHK4e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e5“AHK3 had an approximately 10-fold lower affinity to isopentenyladenine (iP) and its riboside, but a higher affinity to dihydrozeatin than CRE1/AHK4”
Claim · model-written summary
For AHK3, cytokinin ribosides (tZR, iPR) and cis-zeatin had true binding activity, lower than that of tZ.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AHK3e6
- Compound
- cytokinin ribosides (tZR, iPR) and cis-zeatine6
- Outcome
- true binding activitye6
- Direction
- lowere6
- Comparator
- tZe6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e6“For AHK3, cytokinin ribosides (tZR, iPR) and cis-zeatin had true binding activity, although lower than that of tZ”
Claim · model-written summary
Thidiazuron was a strong competitor for cytokinin binding to AHK3.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- thidiazurone7
- Outcome
- a strong competitore7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e7“The phenylurea-derived cytokinin thidiazuron was a strong competitor and bound to the same site as did adenine-derived cytokinins”
Claim · model-written summary
Thidiazuron bound to the same site as adenine-derived cytokinins.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- thidiazurone7
- Outcome
- bound to the same sitee7
- Comparator
- adenine-derived cytokininse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e7“The phenylurea-derived cytokinin thidiazuron was a strong competitor and bound to the same site as did adenine-derived cytokinins”
Claim · model-written summary
Butan-1-ol, an inhibitor of cytokinin action, had little effect on cytokinin-receptor complex formation.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- inhibitor of cytokinin action butan-1-ole7
- Outcome
- cytokinin-receptor complex formatione7
- Direction
- little effecte7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e7“The inhibitor of cytokinin action butan-1-ol had little effect on cytokinin-receptor complex formation”
Claim · model-written summary
The binding properties of AHK3 suggest a specific function in root-to-shoot communication.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AHK3e7
- Outcome
- specific function in root-to-shoot communicatione7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis cytokinin receptor AHK3”
e7“The revealed properties of AHK3 suggest its specific function in root-to-shoot communication”
The same questions in other papers
class · physiology: hormones · ArabidopsisPositive and negative results
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