2026-09-09 REL RCSB INITIAL_RELEASE REPOSITORY INITIAL_RELEASE REPOSITORY RCSB RCSB 2026-03-18 2026-09-09 2026-09-09 2026-09-09 National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS) United States Richard and Susan Smith Family Foundation United States The Giovanni Armenise-Harvard Foundation United States Zhou H Brown A Cilia, Transition Zone, DMT, MIPs, cryoET, STRUCTURAL PROTEIN Zhou H Brown A Science US 2026 doi:10.1126/science.aei5957 1095-9203 0038 SCIEAS EMD-75919 consensus EM volume EMD-75912 focused EM volume EMD-75913 focused EM volume EMD-75916 focused EM volume EMD-75917 focused EM volume EMD-75920 focused EM volume 11yj FULLOVERLAP EMDB EMD-75919 consensus EM volume EMDB EMD-75912 focused EM volume EMDB EMD-75913 focused EM volume EMDB EMD-75916 focused EM volume EMDB EMD-75917 focused EM volume EMDB EMD-75920 focused EM volume EMDB EMD-76188 associated EM volume

In situ subtomogram average of the transition zone doublet microtubule in human airway cilia (composite map)

Transition zone DMT with MIPs repeat every 8 nm Transition zone DMT with MIPs repeat every 8 nm 0 1 2 3 4 5 6 7 Homo sapiens Tubulin alpha-1A chain Homo sapiens 0.05018844099999999 77 LEVO MRECISIHVGQAGVQIGNACWELYCLEHGIQPDGQMPSDKTIGGGDDSFNTFFSETGAGKHVPRAVFVDLEPTVIDEVRT GTYRQLFHPEQLITGKEDAANNYARGHYTIGKEIIDLVLDRIRKLADQCTGLQGFLVFHSFGGGTGSGFTSLLMERLSVD YGKKSKLEFSIYPAPQVSTAVVEPYNSILTTHTTLEHSDCAFMVDNEAIYDICRRNLDIERPTYTNLNRLIGQIVSSITA SLRFDGALNVDLTEFQTNLVPYPRIHFPLATYAPVISAEKAYHEQLSVAEITNACFEPANQMVKCDPRHGKYMACCLLYR GDVVPKDVNAAIATIKTKRTIQFVDWCPTGFKVGINYQPPTVVPGGDLAKVQRAVCMLSNTTAIAEAWARLDHKFDLMYA KRAFVHWYVGEGMEEGEFSEAREDMAALEKDYEEVGVDSVEGEGEEEGEEY Q71U36 Tubulin beta-4B chain Homo sapiens 0.049877824 77 LEVO MREIVHLQAGQCGNQIGAKFWEVISDEHGIDPTGTYHGDSDLQLERINVYYNEATGGKYVPRAVLVDLEPGTMDSVRSGP FGQIFRPDNFVFGQSGAGNNWAKGHYTEGAELVDSVLDVVRKEAESCDCLQGFQLTHSLGGGTGSGMGTLLISKIREEYP DRIMNTFSVVPSPKVSDTVVEPYNATLSVHQLVENTDETYCIDNEALYDICFRTLKLTTPTYGDLNHLVSATMSGVTTCL RFPGQLNADLRKLAVNMVPFPRLHFFMPGFAPLTSRGSQQYRALTVPELTQQMFDAKNMMAACDPRHGRYLTVAAVFRGR MSMKEVDEQMLNVQNKNSSYFVEWIPNNVKTAVCDIPPRGLKMSATFIGNSTAIQELFKRISEQFTAMFRRKAFLHWYTG EGMDEMEFTEAESNMNDLVSEYQQYQDATAEEEGEFEEEAEEEVA P68371 Cilia- and flagella-associated protein 20 Homo sapiens 0.022807469 4 LEVO MFKNTFQSGFLSILYSIGSKPLQIWDKKVRNGHIKRITDNDIQSLVLEIEGTNVSTTYITCPADPKKTLGIKLPFLVMII KNLKKYFTFEVQVLDDKNVRRRFRASNYQSTTRVKPFICTMPMRLDDGWNQIQFNLLDFTRRAYGTNYIETLRVQIHANC RIRRVYFSDRLYSEDELPAEFKLYLPVQNKAKQ Q9Y6A4 Centrosomal protein of 41 kDa Homo sapiens 0.041426406 3 LEVO MSLRRHIGNPEYLMKRIPQNPRYQHIKSRLDTGNSMTKYTEKLEEIKKNYRYKKDELFKRLKVTTFAQLIIQVASLSDQT LEVTAEEIQRLEDNDSAASDPDAETTARTNGKGNPGEQSPSPEQFINNAGAGDSSRSTLQSVISGVGELDLDKGPVKKAE PHTKDKPYPDCPFLLLDVRDRDSYQQCHIVGAYSYPIATLSRTMNPYSNDILEYKNAHGKIIILYDDDERLASQAATTMC ERGFENLFMLSGGLKVLAQKFPEGLITGSLPASCQQALPPGSARKRSSPKGPPLPAENKWRFTPEDLKKIEYYLEEEQGP ADHPSRLNQANSSGRESKVPGARSAQNLPGGGPASHSNPRSLSSGHLQGKPWK Q9BYV8 Calcyphosin-like protein Homo sapiens 0.024264686 40 LEVO MAGTARHDREMAIQAKKKLTTATDPIERLRLQCLARGSAGIKGLGRVFRIMDDDNNRTLDFKEFMKGLNDYAVVMEKEEV EELFRRFDKDGNGTIDFNEFLLTLRPPMSRARKEVIMQAFRKLDKTGDGVITIEDLREVYNAKHHPKYQNGEWSEEQVFR KFLDNFDSPYDKDGLVTPEEFMNYYAGVSASIDTDVYFIIMMRTAWKL Q8WWF8 Microtubule-associated protein 9 Homo sapiens 0.074374258 2 LEVO MSDEVFSTTLAYTKSPKVTKRTTFQDELIRAITARSARQRSSEYSDDFDSDEIVSLGDFSDTSADENSVNKKMNDFHISD DEEKNPSKLLFLKTNKSNGNITKDEPVCAIKNEEEMAPDGCEDIVVKSFSESQNKDEEFEKDKIKMKPKPRILSIKSTSS AENNSLDTDDHFKPSPRPRSMLKKKSHMEEKDGLEDKETALSEELELHSAPSSLPTPNGIQLEAEKKAFSENLDPEDSCL TSLASSSLKQILGDSFSPGSEGNASGKDPNEEITENHNSLKSDENKENSFSADHVTTAVEKSKESQVTADDLEEEKAKAE LIMDDDRTVDPLLSKSQSILISTSATASSKKTIEDRNIKNKKSTNNRASSASARLMTSEFLKKSSSKRRTPSTTTSSHYL GTLKVLDQKPSQKQSIEPDRADNIRAAVYQEWLEKKNVYLHEMHRIKRIESENLRIQNEQKKAAKREEALASFEAWKAMK EKEAKKIAAKKRLEEKNKKKTEEENAARKGEALQAFEKWKEKKMEYLKEKNRKEREYERAKKQKEEETVAEKKKDNLTAV EKWNEKKEAFFKQKEKEKINEKRKEELKRAEKKDKDKQAINEYEKWLENKEKQERIERKQKKRHSFLESEALPPWSPPSR TVFAKVF Q49MG5 Enkurin domain-containing protein 1 Homo sapiens 0.038828219 3 LEVO MCEGPSRISGPIPPDPTLCPDNYRRPTSAQGRLEGNALKLDLLTSDRALDTTAPRGPCIGPGAGEILERGQRGVGDVLLQ LEGISLGPGASLKRKDPKDHEKENLRRIREIQKRFREQERSREQGQPRPLKALWRSPKYDKVESRVKAQLQEPGPASGTE SAHFLRAHSRCGPGLPPPHVSSPQPTPPGPEAKEPGLGVDFIRHNARAAKRAPRRHSCSLQVLAQVLEQQRQAQEHYNAT QKGHVPHYLLERRDLWRREAEARKQSQPDPAMPPGHTRMPENQRLETLTKLLQSQSQLLRELVLLPAGADSLRAQSHRAE LDRKLVQVEEAIKIFSRPKVFVKMDD Q9H0I2 GUANOSINE-5'-TRIPHOSPHATE 0.0005231799999999999 77 GTP GUANOSINE-5'-DIPHOSPHATE 0.000443201 77 GDP subtomogramAveraging cell 7.2 ETHANE TFS KRIOS FLOOD BEAM BRIGHT FIELD FIELD EMISSION GUN 300 2.0 4.0 FEI FALCON IV (4k x 4k) 4.68 1 7.3 FSC 0.143 CUT-OFF RELION 5 33196 209 66385 Warp 2.0 PHASE FLIPPING AND AMPLITUDE CORRECTION MAXIMUM LIKELIHOOD

Atomic models were built in Coot. CFAP20 and tubulin models were obtained from PDB: 7UNG and fit as rigid-bodies into the subtomogram average. All other proteins were modeled using AlphaFold3 or Boltz-2 and fit into the density either manually or using DomainSeeker. Initial atomic models were refined into the subtomogram averaging map using rigid-body refinement in phenix.real_space_refine. Geometry outliers were corrected manually in Coot. Final refinement was performed in Phenix using group atomic displacement parameter (ADP) refinement against the subtomogram averages. Side-chain density is not resolved at this resolution, and the model is intended to describe subunit and domain placement rather than atomic-accuracy contacts. The side-chain conformations in the deposited file were inherited from the reference models used to build it rather than determined from our density and should not be interpreted as experimentally determined. The reported contacts trace to a small number of systematic sources rather than many independent modeling errors.