{Reference Type}: Journal Article
{Title}: Plasma Membrane Domain Patterning and Self-Reinforcing Polarity in Arabidopsis.
{Author}: Marhava P;Aliaga Fandino AC;Koh SWH;Jelínková A;Kolb M;Janacek DP;Breda AS;Cattaneo P;Hammes UZ;Petrášek J;Hardtke CS;
{Journal}: Dev Cell
{Volume}: 52
{Issue}: 2
{Year}: 01 2020 27
{Factor}: 13.417
{DOI}: 10.1016/j.devcel.2019.11.015
{Abstract}: Cell polarity is a key feature in the development of multicellular organisms. For instance, asymmetrically localized plasma-membrane-integral PIN-FORMED (PIN) proteins direct transcellular fluxes of the phytohormone auxin that govern plant development. Fine-tuned auxin flux is important for root protophloem sieve element differentiation and requires the interacting plasma-membrane-associated BREVIS RADIX (BRX) and PROTEIN KINASE ASSOCIATED WITH BRX (PAX) proteins. We observed "donut-like" polar PIN localization in developing sieve elements that depends on complementary, "muffin-like" polar localization of BRX and PAX. Plasma membrane association and polarity of PAX, and indirectly BRX, largely depends on phosphatidylinositol-4,5-bisphosphate. Consistently, mutants in phosphatidylinositol-4-phosphate 5-kinases (PIP5Ks) display protophloem differentiation defects similar to brx mutants. The same PIP5Ks are in complex with BRX and display "muffin-like" polar localization. Our data suggest that the BRX-PAX module recruits PIP5Ks to reinforce PAX polarity and thereby the polarity of all three proteins, which is required to maintain a local PIN minimum.