51. COPII proteins exhibit distinct subdomains within each ER exit site for executing their functions
- Author
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Toshiaki Katada, Miharu Maeda, Kota Saito, Akihiko Nakano, and Kazuo Kurokawa
- Subjects
0301 basic medicine ,lcsh:Medicine ,Endoplasmic Reticulum ,Article ,03 medical and health sciences ,0302 clinical medicine ,Protein Domains ,Live cell imaging ,Antigens, Neoplasm ,Guanine Nucleotide Exchange Factors ,Humans ,Secretion ,lcsh:Science ,COPII ,Exit site ,Multidisciplinary ,Chemistry ,Endoplasmic reticulum ,Aryl Hydrocarbon Receptor Nuclear Translocator ,lcsh:R ,Coat complexes ,Transmembrane protein ,Cell biology ,Neoplasm Proteins ,DNA-Binding Proteins ,030104 developmental biology ,Secretory protein ,lcsh:Q ,COP-Coated Vesicles ,030217 neurology & neurosurgery ,Function (biology) ,HeLa Cells ,Transcription Factors - Abstract
Secretory proteins are exported from special domains of the endoplasmic reticulum (ER) termed ER exit sites, via COPII-coated carriers. We recently showed that TANGO1 and Sec16 cooperatively organize mammalian ER exit sites for efficient secretion. However, the detailed spatial organization of mammalian ER exit sites is yet to be revealed. Here, we used super-resolution confocal live imaging microscopy (SCLIM) to investigate the localization of endogenous proteins, and we identified domains abundant in transmembrane complexes (TANGO1/cTAGE5/Sec12) juxtaposed to Sec16. Interestingly, this domain can be distinguished from the inner and the outer coats of COPII proteins within each mammalian ER exit site. Cargoes are partially concentrated in the domain for secretion. Our results suggest that mammalian ER exit sites compartmentalize proteins according to their function in COPII vesicle formation.
- Published
- 2019