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PLoS One. 2015 Mar 19;10(3):e0117074. doi: 10.1371/journal.pone.0117074. eCollection 2015.

Proteomic analysis of proteins surrounding occludin and claudin-4 reveals their proximity to signaling and trafficking networks.

Author information

1
Laboratory of Tight Junction Structure and Function, NHLBI, National Institutes of Health, Bethesda, MD, United States of America.
2
Proteomics Core Facility, NHLBI, National Institutes of Health, Bethesda, MD, United States of America.

Abstract

Tight junctions are complex membrane structures that regulate paracellular movement of material across epithelia and play a role in cell polarity, signaling and cytoskeletal organization. In order to expand knowledge of the tight junction proteome, we used biotin ligase (BioID) fused to occludin and claudin-4 to biotinylate their proximal proteins in cultured MDCK II epithelial cells. We then purified the biotinylated proteins on streptavidin resin and identified them by mass spectrometry. Proteins were ranked by relative abundance of recovery by mass spectrometry, placed in functional categories, and compared not only among the N- and C- termini of occludin and the N-terminus of claudin-4, but also with our published inventory of proteins proximal to the adherens junction protein E-cadherin and the tight junction protein ZO-1. When proteomic results were analyzed, the relative distribution among functional categories was similar between occludin and claudin-4 proximal proteins. Apart from already known tight junction- proteins, occludin and claudin-4 proximal proteins were enriched in signaling and trafficking proteins, especially endocytic trafficking proteins. However there were significant differences in the specific proteins comprising the functional categories near each of the tagging proteins, revealing spatial compartmentalization within the junction complex. Taken together, these results expand the inventory of known and unknown proteins at the tight junction to inform future studies of the organization and physiology of this complex structure.

PMID:
25789658
PMCID:
PMC4366163
DOI:
10.1371/journal.pone.0117074
[Indexed for MEDLINE]
Free PMC Article

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