Formins are a large, evolutionarily old family of cytoskeletal regulators whose roles include actin capping and nucleation, as well as modulation of microtubule dynamics. The plant class I formin clade is characterized by a unique domain organization, as most of its members are transmembrane proteins with possible cell wall-binding motifs exposed to the extracytoplasmic space-a structure that appears to be a synapomorphy of the plant kingdom. While such transmembrane formins are traditionally considered mainly as plasmalemma-localized proteins contributing to the organization of the cell cortex, we review, from a cell biology perspective, the growing evidence that they can also, at least temporarily, reside (and in some cases also function) in endomembranes including secretory and endocytotic pathway compartments, the endoplasmic reticulum, the nuclear envelope, and the tonoplast. Based on this evidence, we propose that class I formins may thus serve as 'active cargoes' of membrane trafficking-membrane-embedded proteins that modulate the fate of endo- or exocytotic compartments while being transported by them.

• Klíčová slova
• Actin, biotic interactions, cell growth, cytokinesis, endocytosis, exocytosis, formin, microtubules, plasmalemma, tonoplast,
• MeSH
• buněčná membrána * metabolismus   MeSH
• forminy * metabolismus   MeSH
• membránové proteiny metabolismus   genetika   MeSH
• rostlinné proteiny metabolismus   genetika   MeSH
• transport proteinů * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• forminy * MeSH
• membránové proteiny MeSH
• rostlinné proteiny MeSH

Fluorescence light microscopy provided convincing evidence for the domain organization of plant plasma membrane (PM) proteins. Both peripheral and integral PM proteins show an inhomogeneous distribution within the PM. However, the size of PM nanodomains and protein clusters is too small to accurately determine their dimensions and nano-organization using routine confocal fluorescence microscopy and super-resolution methods. To overcome this limitation, we have developed a novel correlative light electron microscopy method (CLEM) using total internal reflection fluorescence microscopy (TIRFM) and advanced environmental scanning electron microscopy (A-ESEM). Using this technique, we determined the number of auxin efflux carriers from the PINFORMED (PIN) family (NtPIN3b-GFP) within PM nanodomains of tobacco cell PM ghosts. Protoplasts were attached to coverslips and immunostained with anti-GFP primary antibody and secondary antibody conjugated to fluorochrome and gold nanoparticles. After imaging the nanodomains within the PM with TIRFM, the samples were imaged with A-ESEM without further processing, and quantification of the average number of molecules within the nanodomain was performed. Without requiring any post-fixation and coating procedures, this method allows to study details of the organization of auxin carriers and other plant PM proteins.

• Klíčová slova
• auxin carriers, correlative microscopy, nanodomains, plasma membrane,
• MeSH
• Arabidopsis genetika   růst a vývoj   MeSH
• buněčná membrána genetika   metabolismus   ultrastruktura   MeSH
• konfokální mikroskopie MeSH
• kovové nanočástice chemie   MeSH
• kyseliny indoloctové metabolismus   MeSH
• mikroskopie elektronová rastrovací * MeSH
• počítačové zpracování obrazu MeSH
• protoplasty metabolismus   ultrastruktura   MeSH
• regulátory růstu rostlin genetika   metabolismus   MeSH
• tabák genetika   metabolismus   ultrastruktura   MeSH
• zlato chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny indoloctové MeSH
• regulátory růstu rostlin MeSH
• zlato MeSH