ID   MUC21_ARATH             Reviewed;         494 AA.
AC   Q9SS43;
DT   26-FEB-2020, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-2000, sequence version 1.
DT   04-NOV-2026, entry version 134.
DE   RecName: Full=Xylan glycosyltransferase MUCI21 {ECO:0000305};
DE            EC=2.4.-.- {ECO:0000305|PubMed:26482889};
DE   AltName: Full=Protein MUCILAGE-MODIFIED 5 {ECO:0000303|PubMed:11706181};
DE   AltName: Full=Protein MUCILAGE-RELATED 21 {ECO:0000303|PubMed:26482889};
DE   AltName: Full=Putative xylan xylosyltransgerase MUCI21 {ECO:0000303|PubMed:26979331};
GN   Name=MUCI21 {ECO:0000303|PubMed:26482889};
GN   Synonyms=MUM5 {ECO:0000303|PubMed:11706181};
GN   OrderedLocusNames=At3g10320 {ECO:0000312|Araport:AT3G10320};
GN   ORFNames=F14P13.8 {ECO:0000312|EMBL:AHL38772.1};
OS   Arabidopsis thaliana (Mouse-ear cress).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; malvids; Brassicales; Brassicaceae; Camelineae; Arabidopsis.
OX   NCBI_TaxID=3702;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=24905498; DOI=10.1111/tpj.12577;
RA   Lao J., Oikawa A., Bromley J.R., McInerney P., Suttangkakul A.,
RA   Smith-Moritz A.M., Plahar H., Chiu T.-Y., Gonzalez Fernandez-Nino S.M.G.,
RA   Ebert B., Yang F., Christiansen K.M., Hansen S.F., Stonebloom S.,
RA   Adams P.D., Ronald P.C., Hillson N.J., Hadi M.Z., Vega-Sanchez M.E.,
RA   Loque D., Scheller H.V., Heazlewood J.L.;
RT   "The plant glycosyltransferase clone collection for functional genomics.";
RL   Plant J. 79:517-529(2014).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=cv. Columbia;
RX   PubMed=11130713; DOI=10.1038/35048706;
RA   Salanoubat M., Lemcke K., Rieger M., Ansorge W., Unseld M., Fartmann B.,
RA   Valle G., Bloecker H., Perez-Alonso M., Obermaier B., Delseny M.,
RA   Boutry M., Grivell L.A., Mache R., Puigdomenech P., De Simone V.,
RA   Choisne N., Artiguenave F., Robert C., Brottier P., Wincker P.,
RA   Cattolico L., Weissenbach J., Saurin W., Quetier F., Schaefer M.,
RA   Mueller-Auer S., Gabel C., Fuchs M., Benes V., Wurmbach E., Drzonek H.,
RA   Erfle H., Jordan N., Bangert S., Wiedelmann R., Kranz H., Voss H.,
RA   Holland R., Brandt P., Nyakatura G., Vezzi A., D'Angelo M., Pallavicini A.,
RA   Toppo S., Simionati B., Conrad A., Hornischer K., Kauer G., Loehnert T.-H.,
RA   Nordsiek G., Reichelt J., Scharfe M., Schoen O., Bargues M., Terol J.,
RA   Climent J., Navarro P., Collado C., Perez-Perez A., Ottenwaelder B.,
RA   Duchemin D., Cooke R., Laudie M., Berger-Llauro C., Purnelle B., Masuy D.,
RA   de Haan M., Maarse A.C., Alcaraz J.-P., Cottet A., Casacuberta E.,
RA   Monfort A., Argiriou A., Flores M., Liguori R., Vitale D., Mannhaupt G.,
RA   Haase D., Schoof H., Rudd S., Zaccaria P., Mewes H.-W., Mayer K.F.X.,
RA   Kaul S., Town C.D., Koo H.L., Tallon L.J., Jenkins J., Rooney T., Rizzo M.,
RA   Walts A., Utterback T., Fujii C.Y., Shea T.P., Creasy T.H., Haas B.,
RA   Maiti R., Wu D., Peterson J., Van Aken S., Pai G., Militscher J.,
RA   Sellers P., Gill J.E., Feldblyum T.V., Preuss D., Lin X., Nierman W.C.,
RA   Salzberg S.L., White O., Venter J.C., Fraser C.M., Kaneko T., Nakamura Y.,
RA   Sato S., Kato T., Asamizu E., Sasamoto S., Kimura T., Idesawa K.,
RA   Kawashima K., Kishida Y., Kiyokawa C., Kohara M., Matsumoto M., Matsuno A.,
RA   Muraki A., Nakayama S., Nakazaki N., Shinpo S., Takeuchi C., Wada T.,
RA   Watanabe A., Yamada M., Yasuda M., Tabata S.;
RT   "Sequence and analysis of chromosome 3 of the plant Arabidopsis thaliana.";
RL   Nature 408:820-822(2000).
RN   [3]
RP   GENOME REANNOTATION.
RC   STRAIN=cv. Columbia;
RX   PubMed=27862469; DOI=10.1111/tpj.13415;
RA   Cheng C.Y., Krishnakumar V., Chan A.P., Thibaud-Nissen F., Schobel S.,
RA   Town C.D.;
RT   "Araport11: a complete reannotation of the Arabidopsis thaliana reference
RT   genome.";
RL   Plant J. 89:789-804(2017).
RN   [4]
RP   GENOME REANNOTATION.
RC   STRAIN=cv. Columbia;
RG   The Arabidopsis Information Resource (TAIR);
RT   "Community-consensus reference genome of Arabidopsis thaliana Col-0.";
RL   Submitted (FEB-2026) to the EMBL/GenBank/DDBJ databases.
RN   [5]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
RC   STRAIN=cv. Columbia;
RX   PubMed=14593172; DOI=10.1126/science.1088305;
RA   Yamada K., Lim J., Dale J.M., Chen H., Shinn P., Palm C.J., Southwick A.M.,
RA   Wu H.C., Kim C.J., Nguyen M., Pham P.K., Cheuk R.F., Karlin-Newmann G.,
RA   Liu S.X., Lam B., Sakano H., Wu T., Yu G., Miranda M., Quach H.L.,
RA   Tripp M., Chang C.H., Lee J.M., Toriumi M.J., Chan M.M., Tang C.C.,
RA   Onodera C.S., Deng J.M., Akiyama K., Ansari Y., Arakawa T., Banh J.,
RA   Banno F., Bowser L., Brooks S.Y., Carninci P., Chao Q., Choy N., Enju A.,
RA   Goldsmith A.D., Gurjal M., Hansen N.F., Hayashizaki Y., Johnson-Hopson C.,
RA   Hsuan V.W., Iida K., Karnes M., Khan S., Koesema E., Ishida J., Jiang P.X.,
RA   Jones T., Kawai J., Kamiya A., Meyers C., Nakajima M., Narusaka M.,
RA   Seki M., Sakurai T., Satou M., Tamse R., Vaysberg M., Wallender E.K.,
RA   Wong C., Yamamura Y., Yuan S., Shinozaki K., Davis R.W., Theologis A.,
RA   Ecker J.R.;
RT   "Empirical analysis of transcriptional activity in the Arabidopsis
RT   genome.";
RL   Science 302:842-846(2003).
RN   [6]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
RC   STRAIN=cv. Columbia;
RA   Totoki Y., Seki M., Ishida J., Nakajima M., Enju A., Kamiya A.,
RA   Narusaka M., Shin-i T., Nakagawa M., Sakamoto N., Oishi K., Kohara Y.,
RA   Kobayashi M., Toyoda A., Sakaki Y., Sakurai T., Iida K., Akiyama K.,
RA   Satou M., Toyoda T., Konagaya A., Carninci P., Kawai J., Hayashizaki Y.,
RA   Shinozaki K.;
RT   "Large-scale analysis of RIKEN Arabidopsis full-length (RAFL) cDNAs.";
RL   Submitted (JUL-2006) to the EMBL/GenBank/DDBJ databases.
RN   [7]
RP   FUNCTION, AND DISRUPTION PHENOTYPE.
RX   PubMed=11706181; DOI=10.1104/pp.127.3.998;
RA   Western T.L., Burn J., Tan W.L., Skinner D.J., Martin-McCaffrey L.,
RA   Moffatt B.A., Haughn G.W.;
RT   "Isolation and characterization of mutants defective in seed coat mucilage
RT   secretory cell development in Arabidopsis.";
RL   Plant Physiol. 127:998-1011(2001).
RN   [8]
RP   FUNCTION, CATALYTIC ACTIVITY, SUBCELLULAR LOCATION, DEVELOPMENTAL STAGE,
RP   AND DISRUPTION PHENOTYPE.
RX   PubMed=26482889; DOI=10.1104/pp.15.01441;
RA   Voiniciuc C., Guenl M., Schmidt M.H., Usadel B.;
RT   "Highly branched xylan made by IRREGULAR XYLEM14 and MUCILAGE-RELATED21
RT   links mucilage to Arabidopsis seeds.";
RL   Plant Physiol. 169:2481-2495(2015).
RN   [9]
RP   FUNCTION, DEVELOPMENTAL STAGE, AND DISRUPTION PHENOTYPE.
RX   PubMed=26979331; DOI=10.1104/pp.16.00211;
RA   Ralet M.C., Crepeau M.J., Vigouroux J., Tran J., Berger A., Salle C.,
RA   Granier F., Botran L., North H.M.;
RT   "Xylans provide the structural driving force for mucilage adhesion to the
RT   Arabidopsis seed coat.";
RL   Plant Physiol. 171:165-178(2016).
CC   -!- FUNCTION: Glycosyletransferase required for the proper composition and
CC       structural properties of released seed coat mucilage (PubMed:11706181,
CC       PubMed:26482889, PubMed:26979331). Required for the production of
CC       highly branched xylan polymers in seed coat mucilage (PubMed:26482889).
CC       Facilitates the addition of xylose residues directly to the xylan
CC       backbone (PubMed:26482889, PubMed:26979331). Xylan with xylose side
CC       chains seems to be necessary for pectin attachment to the seed surface
CC       (PubMed:26482889, PubMed:26979331). Essential for xylan synthesis in
CC       seed coat epidermal (SCE) cells (PubMed:26482889).
CC       {ECO:0000269|PubMed:11706181, ECO:0000269|PubMed:26482889,
CC       ECO:0000269|PubMed:26979331}.
CC   -!- SUBCELLULAR LOCATION: Golgi apparatus membrane
CC       {ECO:0000269|PubMed:26482889}; Single-pass type II membrane protein
CC       {ECO:0000255}.
CC   -!- DEVELOPMENTAL STAGE: Expressed in the seed coat at the linear cotyledon
CC       and mature green stages, when mucilage synthesis occurs.
CC       {ECO:0000269|PubMed:26482889, ECO:0000269|PubMed:26979331}.
CC   -!- DISRUPTION PHENOTYPE: Reduced amount and altered composition of seed
CC       coat mucilage. {ECO:0000269|PubMed:11706181,
CC       ECO:0000269|PubMed:26482889, ECO:0000269|PubMed:26979331}.
CC   -!- SIMILARITY: Belongs to the glycosyltransferase 61 family.
CC       {ECO:0000305}.
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DR   EMBL; KJ138832; AHL38772.1; -; mRNA.
DR   EMBL; AC009400; AAF02811.1; -; Genomic_DNA.
DR   EMBL; CP002686; AEE74891.1; -; Genomic_DNA.
DR   EMBL; OZ408685; CAO7040333.1; -; Genomic_DNA.
DR   EMBL; BT005786; AAO64189.1; -; mRNA.
DR   EMBL; BT006103; AAP04088.1; -; mRNA.
DR   EMBL; AK228390; BAF00327.1; -; mRNA.
DR   RefSeq; NP_187643.1; NM_111867.4.
DR   AlphaFoldDB; Q9SS43; -.
DR   SMR; Q9SS43; -.
DR   FunCoup; Q9SS43; 450.
DR   STRING; 3702.Q9SS43; -.
DR   GlyCosmos; Q9SS43; 1 site, No reported glycans.
DR   GlyGen; Q9SS43; 1 site.
DR   PaxDb; 3702-Q9SS43; -.
DR   ProteomicsDB; 191381; -.
DR   GeneID; 820194; -.
DR   KEGG; ath:AT3G10320; -.
DR   Araport; AT3G10320; -.
DR   TAIR; AT3G10320; MUCI21.
DR   eggNOG; KOG4698; Eukaryota.
DR   HOGENOM; CLU_016869_0_3_1; -.
DR   InParanoid; Q9SS43; -.
DR   OMA; AAHRYSG; -.
DR   PhylomeDB; Q9SS43; -.
DR   PRO; PR:Q9SS43; -.
DR   Proteomes; UP000006548; Chromosome 3.
DR   Proteomes; UP001984100; Chromosome 3.
DR   GO; GO:0005794; C:Golgi apparatus; IDA:TAIR.
DR   GO; GO:0000139; C:Golgi membrane; EXP:UniProtKB.
DR   GO; GO:0047517; F:1,4-beta-D-xylan synthase activity; IMP:TAIR.
DR   GO; GO:0016757; F:glycosyltransferase activity; IBA:GO_Central.
DR   GO; GO:0010192; P:mucilage biosynthetic process; IMP:TAIR.
DR   GO; GO:0048354; P:mucilage biosynthetic process involved in seed coat development; IMP:TAIR.
DR   InterPro; IPR049625; Glyco_transf_61_cat.
DR   InterPro; IPR007657; Glycosyltransferase_61.
DR   PANTHER; PTHR20961; GLYCOSYLTRANSFERASE; 1.
DR   PANTHER; PTHR20961:SF65; XYLAN GLYCOSYLTRANSFERASE MUCI21; 1.
DR   Pfam; PF04577; Glyco_transf_61; 1.
PE   1: Evidence at protein level;
KW   Cell wall biogenesis/degradation; Glycoprotein; Glycosyltransferase;
KW   Golgi apparatus; Membrane; Reference proteome; Signal-anchor; Transferase;
KW   Transmembrane; Transmembrane helix.
FT   CHAIN           1..494
FT                   /note="Xylan glycosyltransferase MUCI21"
FT                   /id="PRO_0000449117"
FT   TOPO_DOM        1..40
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000305"
FT   TRANSMEM        41..61
FT                   /note="Helical; Signal-anchor for type II membrane protein"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        62..494
FT                   /note="Lumenal"
FT                   /evidence="ECO:0000305"
FT   CARBOHYD        375
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00498"
SQ   SEQUENCE   494 AA;  57287 MW;  2AD6763BA8F23CF4 CRC64;
     MRQNLKKVAQ IKVDESKKLF PYVFRVKTSC GNCAKRSKPK LIYLLIFSLI SSCFVFAPQL
     LCFPYPSALF LIDSSIKEIE NRVSESNIES PKTSQKEESI SCDRTGYRSD ICFMKGDIRT
     HSPSSSIFLY TSNDLTTDQV LQEKIKPYTR KWETSIMETI PELKLVTKDM KLFGDKRKCE
     VIHEVPAVLF STGGYTGNLY HEFNDGLIPL YITSKRFNKK VVFVIAEYHK WWEMKYGDVL
     SQLSDYSLID FNKDKRTHCF KEAIVGLRIH GELTVDPSQM QDDGTTINEF RNVLDRAYRP
     RINRLDRLEE QRFHARLAQR RKAKRPKLAL FSRTGSRGIT NEDLMVKMAQ RIGFDIEVLR
     PDRTTELAKI YRVLNSSKVM VGVHGAAMTH FLFMKPGSIF IQIIPLGTDW AAETYYGEPA
     KKLGLDYNGY KILPRESSLY EKYDKDDPIL KDPNSITKKG WQFTKGIYLN DQKVRLDLHR
     FKKLLIDAYA KSIR
//