Membrane proteins of the endoplasmic reticulum induce high-curvature tubules.
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.
Hu
Junjie
J
Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Shibata
Yoko
Y
Voss
Christiane
C
Shemesh
Tom
T
Li
Zongli
Z
Coughlin
Margaret
M
Kozlov
Michael M
MM
Rapoport
Tom A
TA
Prinz
William A
WA
D000595:Amino Acid Sequence; D000818:Animals; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D019556:COS Cells; D002522:Chlorocebus aethiops; D004721:Endoplasmic Reticulum / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D057927:Hydrophobic and Hydrophilic Interactions; D007425:Intracellular Membranes / Q000737:chemistry / Q000648:ultrastructure; D008051:Lipid Bilayers; D008563:Membrane Lipids / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D008854:Microscopy, Electron; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011510:Proteolipids / Q000737:chemistry; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D001704:Biopolymers; D008051:Lipid Bilayers; D008563:Membrane Lipids; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D050505:Mutant Proteins; D011510:Proteolipids; C505725:Rtn1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C426246:YOP1 protein, S cerevisiae; C020485:proteoliposomes