Intracellular Trafficking and Imaging Methods of Membrane-Bound Transcription Factors in Plants

Abstract Membrane-bound transcription factors (MTFs) differ from cytosolic transcription factors (TFs) and they innately bind to membranes. Under external stimuli, MTFs are released from various membranes, convert into the active form, and are transported into the nucleus for transcriptional regulation. Therefore, unlike most TFs, MTFs go through the unique process of transitioning from the membrane to intracellular regions. There are two typical mechanisms during this period: proteolytic processing and alternative splicing. However, other activation schemes have also recently emerged. To further understand these mechanisms, it is essential to study how MTFs transport within the cell and into the nucleus. Imaging techniques with high spatiotemporal resolution can partially resolve this process but new methods are required for future studies. In this review, we give an overview of the current knowledge of plant MTFs, including their identification, specific localization, and the difficulties in studying their cellular dynamics. We also discuss molecular mechanisms of MTF release and advanced methods, such as fluorescence correlation spectroscopy, single-particle tracking, and photoactivated localization microscopy, to further reveal their intracellular movement in living cells.