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Polar auxin transport , which takes place with the carrier protein , is a unique way to distribute auxin in plant enabling the formation in particular cells or tissues phytohormone concentration gradient . The auxin transport protein involved belong to three families : media PIN (PIN -formed ) , the pump PGP / ABCb ( P-glycoprotein/ATP binding cassette ) and permease AUX1/LAX ( auxina RESISTANT1/LIKE-AUX1 ) . The results of recent studies have confirmed that five of the eight PIN proteins in A. thaliana , functioning as carriers transporting auxin out of the cell . Proteins PGP / ABCb , carriers belonging to the superfamily of ATP- binding cassette , constitute the second group of the auxin transporters pumping cell to the extracellular space . In the family of proteins preferably in A. thaliana PGP1/ABCB1 characterized transporters , and PGP4/ABCB4 PGP19/ABCB19 . Recent studies suggest that PIN and PGP proteins , functioning as an independent export auxin transporters themselves, interact in vivo transport phytohormone . The auxin transport from the apoplast into the cell participates symporter AUX1 and three of its functional analogues LIKE - AUX1 . The problem now focused the attention of many researchers is unusual flexibility redistribution mechanisms within the cell auxin transport proteins , are manifest as key elements governing the polar transport of phytohormone . Intracellular relocation of auxin transporters , made ​​possible by the recycling constitutive protein comprises endocytic internalization and transfer of proteins to the endosomal membrane trafficking , and then their return to their transport through the cell membrane egzocytarnemu . Recent studies have shown that internalisation PIN proteins is via vesicular transport clathrin -dependent . Back transporters from different compartments of the plasma membrane to endosomes or lytic vacuolar transport is subject to complex regulation mediated by the small G-proteins and complexes retromerowe AGCVIII protein kinases subfamily . Changes in the location of the membrane protein was observed in the PIN embryogenesis , initiation of lateral roots filotaksji , and in some responses tropic . It has been shown that grawistymulacja root cells received by kolumelli , PIN3 changes the location of the polar apolar , leading to an asymmetric distribution of auxin in the elongation of the root portion . Similarly , the response in the form of bending fototropowa hypocotyle , remaining in close connection with the uneven distribution of auxin is dependent on the location of the polar PIN3 endoderm cells .

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The Editorial Board
Andrzej Łukaszyk - przewodniczący, Zofia Bielańska-Osuchowska, Szczepan Biliński, Mieczysław Chorąży, Aleksander Koj, Włodzimierz Korochoda, Leszek Kuźnicki, Aleksandra Stojałowska, Lech Wojtczak

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