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.

• MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   MeSH
• buněčná diferenciace * MeSH
• buněčná membrána metabolismus   MeSH
• fosfatasy genetika   metabolismus   MeSH
• fosfotransferasy s alkoholovou skupinou jako akceptorem metabolismus   MeSH
• kořeny rostlin genetika   růst a vývoj   metabolismus   MeSH
• mutace MeSH
• polarita buněk * MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin * MeSH
• transkripční faktory paired box genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH