ABSTRACT The fusion of mononucleated myoblasts produces multinucleated muscle fibers leading to the formation of skeletal muscle. Myomaker, a skeletal muscle-specific membrane protein, is

essential for myoblast fusion. Here we report the cryo-EM structures of mouse Myomaker (mMymk) and _Ciona robusta_ Myomaker (cMymk). Myomaker contains seven transmembrane helices (TMs) that

adopt a G-protein-coupled receptor-like fold. TMs 2–4 form a dimeric interface, while TMs 3 and 5–7 create a lipid-binding site that holds the polar head of a phospholipid and allows the

alkyl tails to insert into Myomaker. The similarity of cMymk and mMymk suggests a conserved Myomaker-mediated cell fusion mechanism across evolutionarily distant species. Functional analyses

Buy or subscribe This is a preview of subscription content, access via your institution ACCESS OPTIONS Access through your institution Access Nature and 54 other Nature Portfolio journals

Get Nature+, our best-value online-access subscription $29.99 / 30 days cancel any time Learn more Subscribe to this journal Receive 12 print issues and online access $209.00 per year only

$17.42 per issue Learn more Buy this article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which are calculated during checkout

ADDITIONAL ACCESS OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS MYOMERGER PROMOTES FUSION

PORE BY ELASTIC COUPLING BETWEEN PROXIMAL MEMBRANE LEAFLETS AND HEMIFUSION DIAPHRAGM Article Open access 21 January 2021 WNT-ROR-DVL SIGNALLING AND THE DYSTROPHIN COMPLEX ORGANIZE

PLANAR-POLARIZED MEMBRANE COMPARTMENTS IN _C. ELEGANS_ MUSCLES Article Open access 10 June 2024 TGFΒ SIGNALLING ACTS AS A MOLECULAR BRAKE OF MYOBLAST FUSION Article Open access 02 February

2021 DATA AVAILABILITY Sequences of the anti-Myomaker antibody candidates were analyzed with the IMGT database (http://www.imgt.org/). The 3D cryo-EM density maps have been deposited in the

Electron Microscopy Data Bank under the accession numbers EMD-40933 (mMymk in detergent), EMD-40934 (mMymk in nanodiscs), EMD-40935 (cMymk), EMD-40936 (mMymkR107A) and EMD-40937

(mMymkY118A). Atomic coordinates for the atomic model have been deposited in the Protein Data Bank (PDB) under the accession numbers 8T03 (mMymk in detergent), 8T04 (mMymk in nanodiscs),

8T05 (cMymk), 8T06 (mMymkR107A) and 8T07 (mMymkY118A). Additional data supporting the findings in this study are provided as source data and supplementary information to this paper.

REFERENCES * Kim, J. H., Jin, P., Duan, R. & Chen, E. H. Mechanisms of myoblast fusion during muscle development. _Curr. Opin. Genet Dev._ 32, 162–170 (2015). CAS  PubMed  PubMed Central

  Google Scholar  * Buckingham, M. Myogenic progenitor cells and skeletal myogenesis in vertebrates. _Curr. Opin. Genet Dev._ 16, 525–532 (2006). CAS  PubMed  Google Scholar  * Kim, J. H.

& Chen, E. H. The fusogenic synapse at a glance. _J. Cell Sci_. https://doi.org/10.1242/jcs.213124 (2019). * Demonbreun, A. R., Biersmith, B. H. & McNally, E. M. Membrane fusion in

muscle development and repair. _Semin. Cell Dev. Biol._ 45, 48–56 (2015). CAS  PubMed  PubMed Central  Google Scholar  * Hindi, S. M., Tajrishi, M. M. & Kumar, A. Signaling mechanisms in

mammalian myoblast fusion. _Sci. Signal_ 6, re2 (2013). PubMed  PubMed Central  Google Scholar  * Leikina, E. et al. Myomaker and Myomerger work independently to control distinct steps of

membrane remodeling during myoblast fusion. _Dev. Cell_ 46, 767–780.e767 (2018). CAS  PubMed  PubMed Central  Google Scholar  * Millay, D. P. et al. Myomaker is a membrane activator of

myoblast fusion and muscle formation. _Nature_ 499, 301–305 (2013). CAS  PubMed  PubMed Central  Google Scholar  * Millay, D. P., Sutherland, L. B., Bassel-Duby, R. & Olson, E. N.

Myomaker is essential for muscle regeneration. _Genes Dev._ 28, 1641–1646 (2014). CAS  PubMed  PubMed Central  Google Scholar  * Di Gioia, S. A. et al. A defect in myoblast fusion underlies

Carey-Fineman-Ziter syndrome. _Nat. Commun._ 8, 16077 (2017). PubMed  PubMed Central  Google Scholar  * Hedberg-Oldfors, C., Lindberg, C. & Oldfors, A. Carey-Fineman-Ziter syndrome with

mutations in the myomaker gene and muscle fiber hypertrophy. _Neurol. Genet._ 4, e254 (2018). CAS  PubMed  PubMed Central  Google Scholar  * Jumper, J. et al. Highly accurate protein

structure prediction with AlphaFold. _Nature_ 596, 583–589 (2021). CAS  PubMed  PubMed Central  Google Scholar  * Millay, D. P. et al. Structure-function analysis of myomaker domains

required for myoblast fusion. _Proc. Natl Acad. Sci. Acad._ 113, 2116–2121 (2016). CAS  Google Scholar  * Lee, G. H. et al. A GPI processing phospholipase A2, PGAP6, modulates Nodal

signaling in embryos by shedding CRIPTO. _J. Cell Biol._ 215, 705–718 (2016). CAS  PubMed  PubMed Central  Google Scholar  * Zhang, H. et al. Evolution of a chordate-specific mechanism for

myoblast fusion. _Sci. Adv._ 8, eadd2696 (2022). CAS  PubMed  Google Scholar  * Du, J. et al. Structures of human mGlu2 and mGlu7 homo- and heterodimers. _Nature_ 594, 589–593 (2021). CAS 

PubMed  Google Scholar  * Velazhahan, V. et al. Structure of the class D GPCR Ste2 dimer coupled to two G proteins. _Nature_ 589, 148–153 (2021). CAS  PubMed  Google Scholar  * Soderberg, O.

et al. Characterizing proteins and their interactions in cells and tissues using the in situ proximity ligation assay. _Methods_ 45, 227–232 (2008). PubMed  Google Scholar  * Holm, L. &

Rosenstrom, P. Dali server: conservation mapping in 3D. _Nucleic Acids Res._ 38, W545–W549 (2010). CAS  PubMed  PubMed Central  Google Scholar  * Vasiliauskaite-Brooks, I. et al. Structure

of a human intramembrane ceramidase explains enzymatic dysfunction found in leukodystrophy. _Nat. Commun._ 9, 5437 (2018). CAS  PubMed  PubMed Central  Google Scholar  * Tanabe, H. et al.

Human adiponectin receptor AdipoR1 assumes closed and open structures. _Commun. Biol._ 3, 446 (2020). CAS  PubMed  PubMed Central  Google Scholar  * Waltenspuhl, Y., Schoppe, J., Ehrenmann,

J., Kummer, L. & Pluckthun, A. Crystal structure of the human oxytocin receptor. _Sci. Adv._ 6, eabb5419 (2020). PubMed  PubMed Central  Google Scholar  * Perez-Vargas, J. et al.

Structural basis of eukaryotic cell-cell fusion. _Cell_ 157, 407–419 (2014). CAS  PubMed  Google Scholar  * Zhang, J. et al. Species-specific gamete recognition initiates fusion-driving

trimer formation by conserved fusogen HAP2. _Nat. Commun._ 12, 4380 (2021). CAS  PubMed  PubMed Central  Google Scholar  * Jeong, J. & Conboy, I. M. Phosphatidylserine directly and

positively regulates fusion of myoblasts into myotubes. _Biochem. Biophys. Res. Commun._ 414, 9–13 (2011). CAS  PubMed  PubMed Central  Google Scholar  * Tsuchiya, M. et al. Cell surface

flip-flop of phosphatidylserine is critical for PIEZO1-mediated myotube formation. _Nat. Commun._ 9, 2049 (2018). PubMed  PubMed Central  Google Scholar  * Bi, P. et al. Control of muscle

formation by the fusogenic micropeptide myomixer. _Science_ 356, 323–327 (2017). CAS  PubMed  PubMed Central  Google Scholar  * Lee, D. M. & Chen, E. H. _Drosophila_ myoblast fusion:

invasion and resistance for the ultimate union. _Annu. Rev. Genet._ 53, 67–91 (2019). CAS  PubMed  PubMed Central  Google Scholar  * Srinivas, B. P., Woo, J., Leong, W. Y. & Roy, S. A

conserved molecular pathway mediates myoblast fusion in insects and vertebrates. _Nat. Genet._ 39, 781–786 (2007). CAS  PubMed  Google Scholar  * Long, T., Liu, Y. & Li, X. Molecular

structures of human ACAT2 disclose mechanism for selective inhibition. _Structure_ https://doi.org/10.1016/j.str.2021.07.009 (2021). Article  PubMed  PubMed Central  Google Scholar  * Sun,

Y. & Li, X. Cholesterol efflux mechanism revealed by structural analysis of human ABCA1 conformational states. _Nat. Cardiovasc. Res._ 1, 238–245 (2022). PubMed  PubMed Central  Google

Scholar  * Ritchie, T. K. et al. Chapter 11—reconstitution of membrane proteins in phospholipid bilayer nanodiscs. _Methods Enzymol._ 464, 211–231 (2009). CAS  PubMed  PubMed Central  Google

Scholar  * Liu, Y. et al. Mechanisms and inhibition of Porcupine-mediated Wnt acylation. _Nature_ 607, 816–822 (2022). CAS  PubMed  PubMed Central  Google Scholar  * Guo, X. et al.

Structure and mechanism of human cystine exporter cystinosin. _Cell_ 185, 3739–3752 (2022). CAS  PubMed  PubMed Central  Google Scholar  * Wang, Q. et al. A combination of human broadly

neutralizing antibodies against hepatitis B virus HBsAg with distinct epitopes suppresses escape mutations. _Cell Host Microbe_ 28, 335–349.e336 (2020). CAS  PubMed  PubMed Central  Google

Scholar  * Rasmussen, S. G. et al. Crystal structure of the human beta2 adrenergic G-protein-coupled receptor. _Nature_ 450, 383–387 (2007). CAS  PubMed  Google Scholar  * Mastronarde, D. N.

Automated electron microscope tomography using robust prediction of specimen movements. _J. Struct. Biol._ 152, 36–51 (2005). PubMed  Google Scholar  * Li, X. et al. Electron counting and

beam-induced motion correction enable near-atomic-resolution single-particle cryo-EM. _Nat. Methods_ 10, 584–590 (2013). CAS  PubMed  PubMed Central  Google Scholar  * Zivanov, J. et al. New

tools for automated high-resolution cryo-EM structure determination in RELION-3. _eLife_ https://doi.org/10.7554/eLife.42166 (2018). * Rohou, A. & Grigorieff, N. CTFFIND4: fast and

accurate defocus estimation from electron micrographs. _J. Struct. Biol._ 192, 216–221 (2015). PubMed  PubMed Central  Google Scholar  * Wagner, T. et al. SPHIRE-crYOLO is a fast and

accurate fully automated particle picker for cryo-EM. _Commun. Biol._ 2, 218 (2019). PubMed  PubMed Central  Google Scholar  * Punjani, A., Rubinstein, J. L., Fleet, D. J. & Brubaker, M.

A. cryoSPARC: algorithms for rapid unsupervised cryo-EM structure determination. _Nat. Methods_ 14, 290–296 (2017). CAS  PubMed  Google Scholar  * Emsley, P. & Cowtan, K. Coot:

model-building tools for molecular graphics. _Acta Crystallogr. D_ 60, 2126–2132 (2004). PubMed  Google Scholar  * Adams, P. D. et al. PHENIX: a comprehensive Python-based system for

macromolecular structure solution. _Acta Crystallogr. D_ 66, 213–221 (2010). CAS  PubMed  PubMed Central  Google Scholar  * Murshudov, G. N., Vagin, A. A. & Dodson, E. J. Refinement of

macromolecular structures by the maximum-likelihood method. _Acta Crystallogr. D_ 53, 240–255 (1997). CAS  PubMed  Google Scholar  * Croll, T. I. ISOLDE: a physically realistic environment

for model building into low-resolution electron-density maps. _Acta Crystallogr. D. Struct. Biol._ 74, 519–530 (2018). CAS  PubMed  PubMed Central  Google Scholar  * Chen, V. B. et al.

MolProbity: all-atom structure validation for macromolecular crystallography. _Acta Crystallogr. D_ 66, 12–21 (2010). CAS  PubMed  Google Scholar  * Pettersen, E. F. et al. UCSF ChimeraX:

structure visualization for researchers, educators, and developers. _Protein Sci._ 30, 70–82 (2021). CAS  PubMed  Google Scholar  * Song, K. et al. Heart repair by reprogramming non-myocytes

with cardiac transcription factors. _Nature_ 485, 599–604 (2012). CAS  PubMed  PubMed Central  Google Scholar  * Ramirez-Martinez, A. et al. Impaired activity of the fusogenic micropeptide

Myomixer causes myopathy resembling Carey-Fineman-Ziter syndrome. _J. Clin. Invest._ https://doi.org/10.1172/JCI159002 (2022). Download references ACKNOWLEDGEMENTS The cryo-EM data were

collected at the UT Southwestern Medical Center Cryo-EM Facility (funded in part by the Cancer Prevention and Research Institute of Texas (CPRIT) Core Facility Support Award no. RP170644).

We thank R. Bassel-Duby for guidance and assistance in many aspects of this work, L. Beatty and Y. Qin for cell culture and P. Bi for providing the cDNA of cMymk and helpful discussion. This

work was supported by grant nos. AHA 23EIA1038669 (X.L.), NIH P01 HL160487 (X.L.), R01 GM135343 (X.L.) and R01 AR067294 (E.N.O.), the Robert A. Welch Foundation (grant nos. I-0025 to E.N.O.

and I-1957 to X.L.) and the CPRIT (grant no. RP200103 to E.N.O.). AUTHOR INFORMATION Author notes * These authors contributed equally: Tao Long, Yichi Zhang. AUTHORS AND AFFILIATIONS *

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA Tao Long, Linda Donnelly & Xiaochun Li * Department of Molecular Biology, University of

Texas Southwestern Medical Center, Dallas, TX, USA Yichi Zhang, Hui Li, Yu-Chung Pien, Ning Liu & Eric N. Olson * Department of Biophysics, University of Texas Southwestern Medical

Center, Dallas, TX, USA Xiaochun Li Authors * Tao Long View author publications You can also search for this author inPubMed Google Scholar * Yichi Zhang View author publications You can

also search for this author inPubMed Google Scholar * Linda Donnelly View author publications You can also search for this author inPubMed Google Scholar * Hui Li View author publications

You can also search for this author inPubMed Google Scholar * Yu-Chung Pien View author publications You can also search for this author inPubMed Google Scholar * Ning Liu View author

publications You can also search for this author inPubMed Google Scholar * Eric N. Olson View author publications You can also search for this author inPubMed Google Scholar * Xiaochun Li

View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS T.L., Y.Z., E.N.O. and X.L. designed the research. T.L. performed the biochemical and

structural experiments. T.L. and L.D. screened the monoclonal antibodies. Y.Z., Y.-C.P. and H.L. performed functional analysis. T.L., Y.Z., N.L., E.N.O. and X.L. analyzed the data and

contributed to paper preparation. T.L., Y.Z., E.N.O. and X.L. wrote the paper. E.N.O. and X.L. supervised the project. CORRESPONDING AUTHORS Correspondence to Eric N. Olson or Xiaochun Li.

ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. PEER REVIEW PEER REVIEW INFORMATION _Nature Structural & Molecular Biology_ thanks Stephen Muench,

Pier Lorenzo Puri and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available. Primary Handling Editor: Katarzyna

Ciazynska, in collaboration with the _Nature Structural & Molecular Biology_ team. ADDITIONAL INFORMATION PUBLISHER’S NOTE Springer Nature remains neutral with regard to jurisdictional

claims in published maps and institutional affiliations. EXTENDED DATA EXTENDED DATA FIG. 1 REPRESENTATIVE GEL-FILTRATION CHROMATOGRAMS OF MYOMAKER COMPLEX WITH FAB. A, Fab18G7-bound mMymkWT

in lipid nanodiscs. B, Fab18G7-bound mMymkWT in detergent. C, Fab18G7-bound mMymkR107A in detergent. D, Fab18G7-bound mMymkY118A in detergent. E, Fab1A1-bound cMymkWT in detergent. The

fraction of each complex is shown on SDS–PAGE with molecular markers and proteins indicated. The peak of each excess fab is indicated. Data shown are representative of two independent

experiments. Source data EXTENDED DATA FIG. 2 CRYO-EM ANALYSES OF MMYMK. A and B, Summary of image processing procedures of mMymk in nanodiscs (A) and detergent (B). The cryo-EM 3D classes

and the final cryo-EM map are shown. C, Fourier shell correlation (FSC) curves between two half maps using cryoSPARC output and Angular distribution of the particles used for the final

reconstructions. D, Local resolution of cryo-EM maps. Maps are colored according to local resolution, estimated using cryoSPARC. E, cryo-EM density of the transmembrane helices (TM) and PC

of mMymk in detergent. The model is shown as cartoon with sticks. F, cryo-EM density of water molecules and zinc ion in TMs at 8σ level. The panel was generated by COOT. EXTENDED DATA FIG. 3

CRYO-EM ANALYSES OF CMYMK. A, Summary of image processing procedures of cMymk in detergent. The cryo-EM 3D classes and the final cryo-EM map are shown. B, Fourier shell correlation (FSC)

curves between two half maps using cryoSPARC output and Angular distribution of the particles used for the final reconstructions. C, Local resolution of cryo-EM map. Map is colored according

to local resolution, estimated using cryoSPARC. D, cryo-EM density of the transmembrane helix (TM) and PC of cMymk in detergent. The model is shown as cartoon with sticks. EXTENDED DATA

FIG. 4 STRUCTURES OF DIMERIC GPCRS. A, Overall structure of mGlu2, a Class-C GPCR (PDB: 7EPA), from the side of the membrane (left) and from the extracellular space (right). One protomer is

colored in pink and the other protomer is colored in purple. TM helices are numbered. B, Overall structure of Ste2, a Class-D GPCR (PDB: 7AD3), from the side of the membrane (left) and from

the extracellular space (right). TMs are labeled. One protomer is colored in blue and the other protomer is colored in green. TM helices are numbered. EXTENDED DATA FIG. 5 SCHEMATIC OF

EXPERIMENTAL DESIGN TO VALIDATE THE FUNCTION OF MMYMK. A, Schematic of experimental design to validate _in cis_ dimerization of mMymk by Proximity Ligation Assay (PLA). Created with

BioRender.com. Two primary antibodies of different species were used to detect two signal peptide and flag-tagged (SF) mMymk monomers. The PLA probe binds the primary antibodies in close

proximity to generate the signal. B and C, Trans proximity ligation assay (PLA) was performed on C2C12 myoblasts that express signal peptide Flag-mMymk and detected using mouse Flag (B) and

rabbit Flag (C) antibodies. Representative images of PLA (red) with Flag (green) expressing mMymkWT or mMymk3M are shown. Nuclei were labeled with DAPI (blue). Scale bar, 10 μm. Experiments

were repeated three times with similar results. D, Schematic of experimental design to validate antibody inhibition of mMymk by Ab15G1. Created with BioRender.com. Ab15G1 occupies mMymk

dimers on either cell and would prevent mMymk interaction across cells, thereby inhibiting myoblast fusion. E, Schematic of experimental design to validate _in trans_ interaction of mMymk by

Proximity Ligation Assay (PLA). Created with BioRender.com. C2C12 myoblasts express either signal peptide and flag-tagged (SF) mMymk monomers or signal peptide and HA-tagged (SHA) mMymk

monomers. Two primary antibodies (anti-HA antibody and anti-Flag antibody) from different species were used to detect two mMymk dimers in the neighboring cells. The PLA probe binds the close

primary antibodies to generate localization of the signal. F, Representative images of HA (green) with DAPI (blue) expressing mMymkWT or mMymk3M on C2C12 myoblasts. The images show that HA

antibody binds the two forms of mMymkWT or mMymk3M similarly. Scale bar, 10 μm. Experiments were repeated three times with similar results. EXTENDED DATA FIG. 6 SEQUENCE ALIGNMENT OF MOUSE,

HUMAN, ZEBRAFISH AND _CIONA_ MYOMAKER. A, Sequence alignment. The transmembrane helices (TM), intracellular loops (ICL), extracellular loops (ECL) and the residue numbers of Myomaker are

indicated above the protein sequence. The conserved residues and disulfide bond are highlighted in green and indicated beneath the protein sequence, respectively. The specific residues

necessary for dimerization and lipid binding and Carey-Fineman-Ziter syndrome (CFZS) causing mutations are indicated by purple, blue and red stars, respectively. m, mouse; h, human; z,

zebrafish; c, _Ciona_. B, The distribution of CFZS-causing mutations. EXTENDED DATA FIG. 7 COMPARISON OF MMYMK WITH ITS STRUCTURAL HOMOLOGUES. A, Monomeric structure of mMymk (blue) viewed

from the side of the membrane. B, Overall structure of ACER3 in green (PDB: 6G7O) viewed from the side of the membrane. C, Structural comparison between mMymk in dark blue and ACER3 in

green. D, Structural comparison between mMymk in dark blue and AdipoR1 in cyan (PDB: 6KS0,). E, Structural comparison between mMymk in dark blue and OTR in magenta (PDB: 6TPK). F, Comparison

between catalytic core of ACER3 and mMymk with related residues labeled. Zinc ion is shown as a sphere in gray (mMymk) and orange (ACER3 and AdipoR1). Calcium ion is shown as a sphere in

green (ACER3). 1-Oleylglycerol, which was co-crystallized with ACER3, is shown as sticks in magenta. The PC of mMymk is shown as sticks in yellow. TM helices are numbered. EXTENDED DATA FIG.

8 CRYO-EM ANALYSES OF MMYMK VARIANTS. A, Summary of image processing procedures of mMymkR107A (left) and mMymkY118A (right) in detergent. The cryo-EM 3D classes and the final cryo-EM map

are shown. B, Fourier shell correlation (FSC) curves between two half maps using cryoSPARC output and Angular distribution of the particles used for the final reconstructions. C, Local

resolution of cryo-EM maps. Maps are colored according to local resolution, estimated using cryoSPARC. D, The cryo-EM maps around the position of putative PC in mMymkWT, mMymkR107A, and

mMymkY118A. The cryo-EM maps of mMymkWT were shown at 2.7 Å and 3.3 Å (low-pass filtered by cryoSPARC) resolution, respectively. There is no notable density around the putative PC position

in the cryo-EM maps of mMymkR107A, and mMymkY118A. The modeled PC is shown as sticks in yellow and its map is colored in red. EXTENDED DATA FIG. 9 STRUCTURAL COMPARISON BETWEEN MMYMKWT,

MMYMKR107A AND MMYMKY118A. A, The hydrophilic interaction network in the extracellular leaflet of TMs 4, 5 and 6 between mMymkWT in blue, mMymkR107A in green, mMymkY118A in salmon. Water

molecule and Zinc ion are shown as sphere in white and gray, respectively. B, Structural comparisons among mMymkWT in blue, mMymkR107A in green, mMymkY118A in salmon and the AlphaFold

prediction model of mMymkWT in gray. The arrow indicates the structural shift of TM5. TMs and related residues are labeled. The PC of mMymkWT is shown as sticks in yellow. C, The cryo-EM

maps of ECL2 in mMymkWT, mMymkR107A, and mMymkY118A. The entire cryo-EM map of each structure is shown and the map of ECL2 is colored in red. EXTENDED DATA FIG. 10 AB15G1 BINDS TO THE

EXTRACELLULAR REGIONS OF MMYMK. A, Pull-down assay of Ab15G1 or control antibody (anti-Hemophilus influenza type B antibody) with mMymk or mMymk-Fab18G7 complex detected by Coomassie

staining. The molecular markers (left) and proteins (right) are indicated. Data shown are representative of two independent experiments. B, Immunofluorescence microscopy of live C2C12

myoblasts expressing GFP (green). Endogenous mMymk is stained with Ab15G1. Scale bar, 10 μm. Experiments were repeated three times with similar results. Source data SUPPLEMENTARY INFORMATION

SUPPLEMENTARY INFORMATION Supplementary Table 1. REPORTING SUMMARY PEER REVIEW FILE SOURCE DATA SOURCE DATA FIG. 2 Unprocessed western blots. SOURCE DATA FIG. 2 Statistical source data.

SOURCE DATA FIG. 3 Unprocessed western blots. SOURCE DATA FIG. 3 Statistical source data. SOURCE DATA FIG. 4 Statistical source data. SOURCE DATA EXTENDED DATA FIG. 1 Unprocessed gels.

SOURCE DATA EXTENDED DATA FIG. 10 Unprocessed gel. RIGHTS AND PERMISSIONS Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a

publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing

agreement and applicable law. Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Long, T., Zhang, Y., Donnelly, L. _et al._ Cryo-EM structures of Myomaker reveal a molecular basis

for myoblast fusion. _Nat Struct Mol Biol_ 30, 1746–1754 (2023). https://doi.org/10.1038/s41594-023-01110-8 Download citation * Received: 09 February 2023 * Accepted: 25 August 2023 *

Published: 28 September 2023 * Issue Date: November 2023 * DOI: https://doi.org/10.1038/s41594-023-01110-8 SHARE THIS ARTICLE Anyone you share the following link with will be able to read

this content: Get shareable link Sorry, a shareable link is not currently available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing initiative