bab Motif

These motifs are generally found in right handed helix above the plane of the beta sheet

Almost all the proteins containing parallel beta sheets have this motif. 

The helix is generally not seen below the plane of beta sheets                                           

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#Unit 6. System Physiology – Plant

Auxin transport takes place polarly

Main axes of shoots and roots have apex-base structural polarity

This structural polarity is dependent on the polarity of auxin transport

Went discovered that IAA moves mainly from the apical to basal end

This type of unidirectional transport is termed polar transport

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#Unit 6. System Physiology – Plant

Auxin is the only plant growth hormone known to be transported polarly.  Auxin efflux takes place by PIN proteins

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#Unit 6. System Physiology – Plant

Auxin influx 

Auxin can enter plant cells from any direction by either of two mechanisms:

Passive diffusion of the protonated (IAAH) form across the phospholipid bilayer

Secondary active transport of the dissociated (IAA–) form via a 2H+–IAA– symporter

The dual pathway of auxin uptake arises because the passive permeability of the membrane to auxin depends strongly on the apoplastic pH.

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#Unit 6. System Physiology – Plant

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#Unit 6. System Physiology – Plant

Polar transport require energy and is gravity independent

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#Id: 7521

#Unit 6. System Physiology – Plant

Several compounds have been synthesized that can act as auxin transport inhibitors (ATIs), including

NPA (1-Nnaphthylphthalamic acid)

TIBA (2,3,5-triiodobenzoic acid)

CPD( 2- carboxyphenyl-3-phenylpropane-1,3- dione)

NOA ( naphthoxyacetic acid)

Gravacin