Helix-turn-Helix

Two helices are connected by a small loop or turn

These helices are stabilized by non-polar contacts between the helices

Mostly found in DNA binding proteins, directly involved in DNA binding

Generally consists of 20 amino acids

Second helix is involved in DNA binding, enters in major groove of the target site

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#Id: 10201

#Unit 6. System Physiology – Plant

Cytokinin Primary site of synthesis -- root tips.

High concentrations -- immature seeds and developing fruits

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#Id: 10202

#Unit 6. System Physiology – Plant

Many plant tissues contain the enzyme cytokinin oxidase, which cleaves the side chain from zeatin (both cis and trans), zeatin riboside, iP, and their N-glucosides, but not their O-glucoside derivatives

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#Unit 6. System Physiology – Plant

Biological effects of cytokinins

Removes inhibitory phosphate

Promotes accumulation of G1 cyclins (CycD)

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#Id: 10204

#Unit 6. System Physiology – Plant

Cytokinin has been linked to the activation of a Cdc25- like phosphatase, whose role is to remove an inhibitory phosphate group from the Cdc2 kinase. 

Cytokinins elevate the expression of the CYCD3 gene, which encodes a D-type cyclin'

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#Id: 10205

#Unit 6. System Physiology – Plant

Cytokinin binds to the CRE1 receptors to initiate a response that culminates in the elevation of transcription of the type- BARRs/ type- A ARRs. 

TLS Online TPP Program

#Id: 10206

#Unit 6. System Physiology – Plant