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Updated: Jul 7, 2026

Pulling Membrane Nanotubes from Giant Unilamellar Vesicles
Published on: December 7, 2017
Membrane proteins of the endoplasmic reticulum induce high-curvature tubules
Junjie Hu1, Yoko Shibata, Christiane Voss
1Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Abstract:
The tubular structure of the endoplasmic reticulum (ER) appears to be generated by integral membrane proteins, the reticulons and a protein family consisting of DP1 in mammals and Yop1p in yeast. Here, individual members of these families were found to be sufficient to generate membrane tubules. When we purified yeast Yop1p and incorporated it into proteoliposomes, narrow tubules (approximately 15 to 17 nanometers in diameter) were generated. Tubule formation occurred with different lipids; required essentially only the central portion of the protein, including its two long hydrophobic segments; and was prevented by mutations that affected tubule formation in vivo. Tubules were also formed by reconstituted purified yeast Rtn1p. Tubules made in vitro were narrower than normal ER tubules, due to a higher concentration of tubule-inducing proteins. The shape and oligomerization of the "morphogenic" proteins could explain the formation of the tubular ER.
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