title: A microtubule-independent role of p150glued in secretory cargo concentration at endoplasmic reticulum exit sites.
abstract: Newly synthesized proteins are sorted into COPII-coated transport carriers at the endoplasmic reticulum (ER). Assembly of the COPII coat complex, which occurs at ER exit sites (ERES), is initiated by membrane association and GTP loading of SAR1, followed by the recruitment of the SEC23-SEC24 and SEC13-SEC31 subcomplexes. Both of these two subcomplexes stimulate GTP hydrolysis and coat disassembly. This inherent disassembly capacity of COPII complexes needs to be regulated to allow sufficient time for cargo sorting and transport carrier formation. By performing fluorescence recovery after photobleaching (FRAP) and mathematical modeling, we show that p150(glued) (also known as DCTN1), a component of the dynactin complex, stabilizes the COPII pre-budding complex on ER membranes in a microtubule-independent manner. Concentration of the secretory marker ts-O45-G at ERES is reduced in the presence of a C-terminal p150(glued) fragment that prevents binding of endogenous p150(glued) to SEC23. A similar cargo reduction is observed upon p150(glued) knockdown. Taken together, our data suggest that cargo concentration at ERES is regulated by p150(glued) to coordinate protein sorting and transport carrier formation with the subsequent long-range transport towards the Golgi complex along microtubules.
authors.affiliation: Cell Biology and Biophysics Unit, EMBL, Meyerhofstraße 1, Heidelberg D-69117, Germany.
authors.forename: Fatima
authors.initials: F
authors.lastname: Verissimo
authors.affiliation: Cell Biology and Biophysics Unit, EMBL, Meyerhofstraße 1, Heidelberg D-69117, Germany.
authors.forename: Aliaksandr
authors.initials: A
authors.lastname: Halavatyi
authors.affiliation: Cell Biology and Biophysics Unit, EMBL, Meyerhofstraße 1, Heidelberg D-69117, Germany matthias.weiss@uni-bayreuth.de pepperko@embl-heidelberg.de.
authors.forename: Rainer
authors.initials: R
authors.lastname: Pepperkok
authors.affiliation: Experimental Physics I, Universitaetsstr. 30, University of Bayreuth, Bayreuth D-95440, Germany matthias.weiss@uni-bayreuth.de pepperko@embl-heidelberg.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Weiss
mesh_terms: D022181:COP-Coated Vesicles / Q000235:genetics / Q000378:metabolism; D000072159:Dynactin Complex; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D011485:Protein Binding
chemical_list: C000606360:DCTN1 protein, human; D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins
keywords: ER exit sites; Endoplasmic reticulum; FRAP; Microtubules; Modeling; Protein sorting; Secretory pathway