Arabidopsis thaliana PIN-FORMED 3 (AtPIN3)
From Proteopedia
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==AtPIN3== | ==AtPIN3== | ||
| - | + | PIN-FORMED (PIN) proteins in plants are responsible for the polar transport of plant hormone auxin alongside AUXIN TRANSPORTER PROTEIN 1 (AUX1) and ATP-BINDING CASSETTE (ABC) transporters. The polar transport of Auxin is crucial for proper plant growth and development. There are 8 PIN proteins divided into two subfamilies – six long PINs (PIN1-PIN4, PIN6 and PIN7) and two short PINs (PIN 5 and PIN8) that localize in the plasma membrane and the endoplasmic reticulum respectively. AtPIN3 is a long PIN that shares atleast 54% similarity with other long PINS. | |
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<StructureSection load='7wks' size='340' side='right' caption='apo state' scene=''> | <StructureSection load='7wks' size='340' side='right' caption='apo state' scene=''> | ||
</StructureSection> | </StructureSection> | ||
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== Function == | == Function == | ||
| + | Auxin and hence the PIN proteins are involved in many processes like embryogenesis, organogenesis, cell fate determination, and cell division. It also contributes to trophic responses like gravitropism and phototropism. | ||
| - | + | Mutation of PIN genes or their improper localization may lead to many developmental defects like shorter roots, reduced number of lateral roots, root meristem collapse, defective columella cells, abnormal cotyledons and altered leaf venation | |
| - | == | + | == Structure == |
| + | PIN3 is its <scene name='10/1096831/Apo_state_of_pin3/1'>apo state</scene> is a homodimer with 10 transmembrane (TM1-TM10) domains each (Figure 1). Both the N and the C terminal of the protein lie on the extracellular side. The 10 TM domains are divided into two groups a scaffold domain (TM1–2 and 6–7) and a transport domain (TM3–5 and 8–10). | ||
| - | + | The helices 1, 2 and 7 of the scaffold domains are involved in dimerization through symmetric interactions with a surface area of 1516 Å. The tilted TM7 interacts with TM 1, TM2 and TM7 of the other subunit through hydrophobic packaging. TM2 establishes hydrophobic packaging at the base of the dimer. This combined scaffold domain remains static and has the transporter domain on either side of it. | |
| - | + | The transport domain is predicted to undergo up-down rigid-body motion in an elevator-like model (Figure 2). Two weak helices TM4 and TM9 break in the middle and cross and connect to each other as short loops. These may provide a substrate binding site and allow for confirmational changes during auxin transport. A solvent accessible pathway is present between the scaffold and the transport domain. This was suggested as the location for the binding of IAA (green link. The elevator model is supported by a structural alignment of PIN3 in its apo and IAA bound state, which shows a movement of the transport domain 2-3 Å towards the scaffold domain once AA binds. | |
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| + | The protein has a cytosolic domain which contains the cytosolic extension of TM5, an Amphiphilic helix (AH) and 3 beta sheets (β1–3). The loop between the AH and β3 has many phosphorylation sites that regulate the subcellular localization and transport activity of the protein. | ||
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| + | == Green links to be moved == | ||
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| + | You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes. | ||
<scene name='10/1096831/Iaa_bound_state/1'>IAA bound state</scene> <scene name='10/1096831/Iaa_bound_state/2'>IAA2</scene> | <scene name='10/1096831/Iaa_bound_state/1'>IAA bound state</scene> <scene name='10/1096831/Iaa_bound_state/2'>IAA2</scene> | ||
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<scene name='10/1096831/Cytosolic_ah_and_beta-strand/1'>AH and beta-strand</scene> | <scene name='10/1096831/Cytosolic_ah_and_beta-strand/1'>AH and beta-strand</scene> | ||
== References == | == References == | ||
<references/> | <references/> | ||
Revision as of 09:19, 30 November 2025
Contents |
AtPIN3
PIN-FORMED (PIN) proteins in plants are responsible for the polar transport of plant hormone auxin alongside AUXIN TRANSPORTER PROTEIN 1 (AUX1) and ATP-BINDING CASSETTE (ABC) transporters. The polar transport of Auxin is crucial for proper plant growth and development. There are 8 PIN proteins divided into two subfamilies – six long PINs (PIN1-PIN4, PIN6 and PIN7) and two short PINs (PIN 5 and PIN8) that localize in the plasma membrane and the endoplasmic reticulum respectively. AtPIN3 is a long PIN that shares atleast 54% similarity with other long PINS.
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Function
Auxin and hence the PIN proteins are involved in many processes like embryogenesis, organogenesis, cell fate determination, and cell division. It also contributes to trophic responses like gravitropism and phototropism.
Mutation of PIN genes or their improper localization may lead to many developmental defects like shorter roots, reduced number of lateral roots, root meristem collapse, defective columella cells, abnormal cotyledons and altered leaf venation
Structure
PIN3 is its is a homodimer with 10 transmembrane (TM1-TM10) domains each (Figure 1). Both the N and the C terminal of the protein lie on the extracellular side. The 10 TM domains are divided into two groups a scaffold domain (TM1–2 and 6–7) and a transport domain (TM3–5 and 8–10).
The helices 1, 2 and 7 of the scaffold domains are involved in dimerization through symmetric interactions with a surface area of 1516 Å. The tilted TM7 interacts with TM 1, TM2 and TM7 of the other subunit through hydrophobic packaging. TM2 establishes hydrophobic packaging at the base of the dimer. This combined scaffold domain remains static and has the transporter domain on either side of it.
The transport domain is predicted to undergo up-down rigid-body motion in an elevator-like model (Figure 2). Two weak helices TM4 and TM9 break in the middle and cross and connect to each other as short loops. These may provide a substrate binding site and allow for confirmational changes during auxin transport. A solvent accessible pathway is present between the scaffold and the transport domain. This was suggested as the location for the binding of IAA (green link. The elevator model is supported by a structural alignment of PIN3 in its apo and IAA bound state, which shows a movement of the transport domain 2-3 Å towards the scaffold domain once AA binds.
The protein has a cytosolic domain which contains the cytosolic extension of TM5, an Amphiphilic helix (AH) and 3 beta sheets (β1–3). The loop between the AH and β3 has many phosphorylation sites that regulate the subcellular localization and transport activity of the protein.
Green links to be moved
You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.
