{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T18:04:25Z","timestamp":1790877865941,"version":"4.1.0"},"posted":{"date-parts":[[2026,8,18]]},"group-title":"Cell Biology","reference-count":52,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NIH","award":["NIH-R01DK090066, P30DK127984, P01-HL160487, R35 GM149533, and Welch Foundation (I-1957)"],"award-info":[{"award-number":["NIH-R01DK090066, P30DK127984, P01-HL160487, R35 GM149533, and Welch Foundation (I-1957)"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,9,28]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  A missense variant in TM6SF2 (transmembrane 6 superfamily member 2, TM6SF2\n                  <jats:sup>E167K<\/jats:sup>\n                  ) is a major risk factor for steatotic liver disease\n                  <jats:sup>1<\/jats:sup>\n                  , while protecting against coronary artery disease\n                  <jats:sup>2<\/jats:sup>\n                  . TM6SF2 is a polytopic resident protein of the smooth endoplasmic reticulum (ER) and ER-Golgi intermediate compartment that promotes lipidation of hepatic ApoB-containing lipoproteins before secretion into the circulation. Here, we used cryo-electron microscopy (cryo-EM) to determine the structures of TM6SF2 and TM6SF2\n                  <jats:sup>E167K<\/jats:sup>\n                  . TM6SF2 comprises 10 transmembrane helices that bind a single cholesterol molecule within a transmembrane cavity. The protein assembles into homodimers and homotetramers that interact with ApoB. Structural and biochemical analyses show that the E167K substitution reduces cholesterol binding and ApoB interaction without disrupting overall protein structure. Expression of wild-type, but not mutant, TM6SF2 restores hepatic triglyceride secretion in TM6SF2-deficient hepatocytes. Together, these findings establish the structural framework for the bulk lipidation step in hepatic lipoprotein biogenesis, the principal pathway for hepatic triglyceride and cholesterol export into the circulation.\n                <\/jats:p>","DOI":"10.64898\/2026.08.17.745233","type":"posted-content","created":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T13:25:14Z","timestamp":1787059514000},"source":"Crossref","is-referenced-by-count":0,"title":["TM6SF2 is a cholesterol-bound homomultimeric ER membrane protein that binds ApoB and is required for bulk lipidation of VLDL"],"prefix":"10.64898","author":[{"given":"Sen","family":"Hong","sequence":"first","affiliation":[{"name":"The Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"},{"name":"Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"},{"name":"Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jin","family":"Wang","sequence":"additional","affiliation":[{"name":"The Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthew A.","family":"Mitsche","sequence":"additional","affiliation":[{"name":"Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jonathan C.","family":"Cohen","sequence":"additional","affiliation":[{"name":"Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaochun","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Helen H.","family":"Hobbs","sequence":"additional","affiliation":[{"name":"The Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"},{"name":"Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"},{"name":"Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026100110151112000_2026.08.17.745233v2.1","doi-asserted-by":"publisher","DOI":"10.1038\/ng.2901"},{"key":"2026100110151112000_2026.08.17.745233v2.2","doi-asserted-by":"publisher","DOI":"10.1038\/ng.2926"},{"key":"2026100110151112000_2026.08.17.745233v2.3","doi-asserted-by":"publisher","DOI":"10.1126\/science.1204265"},{"key":"2026100110151112000_2026.08.17.745233v2.4","doi-asserted-by":"crossref","unstructured":"Kozlitina, J. , Romeo, S. & Hobbs, H.H. Genetic risk of steatotic liver disease: Pathogenesis, prognosis, and implications for treatment. 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