An in vitro vesicle formation assay reveals cargo clients and factors that mediate vesicular trafficking

Yan Huang, Haidi Yin, Baiying Li, Qian Wu, Yang Liu, Kristina Poljak, Julija Maldutyte, Xiao Tang, Mo Wang, Zhixiao Wu, Elizabeth A. Miller, Liwen Jiang, Zhong Ping Yao*, Yusong Guo*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

20 Citations (Scopus)


The fidelity of protein transport in the secretory pathway relies on the accurate sorting of proteins to their correct destinations. To deepen our understanding of the underlying molecular mechanisms, it is important to develop a robust approach to systematically reveal cargo proteins that depend on specific sorting machinery to be enriched into transport vesicles. Here, we used an in vitro assay that reconstitutes packaging of human cargo proteins into vesicles to quantify cargo capture. Quantitative mass spectrometry (MS) analyses of the isolated vesicles revealed cytosolic proteins that are associated with vesicle membranes in a GTP-dependent manner. We found that two of them, FAM84B (also known as LRAT domain containing 2 or LRATD2) and PRRC1, contain proline-rich domains and regulate anterograde trafficking. Further analyses revealed that PRRC1 is recruited to endoplasmic reticulum (ER) exit sites, interacts with the inner COPII coat, and its absence increases membrane association of COPII. In addition, we uncovered cargo proteins that depend on GTP hydrolysis to be captured into vesicles. Comparing control cells with cells depleted of the cargo receptors, SURF4 or ERGIC53, we revealed specific clients of each of these two export adaptors. Our results indicate that the vesicle formation assay in combination with quantitative MS analysis is a robust and powerful tool to uncover novel factors that mediate vesicular trafficking and to uncover cargo clients of specific cellular factors.

Original languageEnglish
Article numbere2101287118
Number of pages12
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number35
Publication statusPublished - 25 Aug 2021

Scopus Subject Areas

  • General

User-Defined Keywords

  • Cargo receptor
  • Cargo sorting
  • Intracellular protein transport
  • Secretory pathway


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