ID   SIAM_XENTR              Reviewed;         240 AA.
AC   Q28G02;
DT   06-FEB-2007, integrated into UniProtKB/Swiss-Prot.
DT   04-APR-2006, sequence version 1.
DT   03-AUG-2022, entry version 86.
DE   RecName: Full=Homeobox protein siamois;
GN   Name=siamois {ECO:0000250|UniProtKB:Q91848}; ORFNames=TGas088l16.1;
OS   Xenopus tropicalis (Western clawed frog) (Silurana tropicalis).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Amphibia;
OC   Batrachia; Anura; Pipoidea; Pipidae; Xenopodinae; Xenopus; Silurana.
OX   NCBI_TaxID=8364;
RN   [1] {ECO:0000312|EMBL:CAJ83552.1}
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
RC   TISSUE=Gastrula {ECO:0000312|EMBL:CAJ83552.1};
RG   NIH - Xenopus Gene Collection (XGC) project;
RL   Submitted (OCT-2006) to the EMBL/GenBank/DDBJ databases.
CC   -!- FUNCTION: Essential for Wnt/beta-catenin-mediated formation of the
CC       Spemann organizer and for induction of the organizer precursor, the
CC       Nieuwkoop center. Acts as a transcriptional activator, cooperating with
CC       TGFbeta signals to induce a program of organizer-specific gene
CC       expression and to generate an organizer with both head- and trunk-
CC       inducing activity. Activates the head organizer gene cer1 by acting
CC       synergistically with otx2 and mix-A/mix.1 through the 5'-TAATCT-3'
CC       element of the cer1 promoter. Also binds as a complex with lhx1/lim1
CC       and mix-A/mix.1 to the 3x 5'-TAAT-3' element of the cer1 promoter.
CC       Required for subsequent dorsoventral axis formation in the embryo,
CC       dorsalizing ventral mesoderm and cooperating with t/bra to induce
CC       dorsal mesoderm. Also involved in neural induction, inducing the cement
CC       gland and neural tissue in overlying ectoderm. Later in development,
CC       has the second function of indirectly repressing ventral genes,
CC       probably by activating the expression of a transcriptional repressor
CC       (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Nucleus {ECO:0000305}.
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DR   EMBL; CR761649; CAJ83552.1; -; mRNA.
DR   RefSeq; NP_001090821.1; NM_001097352.1.
DR   AlphaFoldDB; Q28G02; -.
DR   SMR; Q28G02; -.
DR   PaxDb; Q28G02; -.
DR   Ensembl; ENSXETT00000019965; ENSXETP00000019965; ENSXETG00000009100.
DR   GeneID; 100038038; -.
DR   KEGG; xtr:100038038; -.
DR   CTD; 100038038; -.
DR   Xenbase; XB-GENE-482368; sia1.
DR   eggNOG; KOG0490; Eukaryota.
DR   InParanoid; Q28G02; -.
DR   OrthoDB; 886524at2759; -.
DR   Proteomes; UP000008143; Chromosome 3.
DR   Proteomes; UP000790000; Unplaced.
DR   Bgee; ENSXETG00000009100; Expressed in upper blastopore lip (Xenopus) and 10 other tissues.
DR   GO; GO:0005634; C:nucleus; IBA:GO_Central.
DR   GO; GO:0005667; C:transcription regulator complex; ISS:UniProtKB.
DR   GO; GO:0000981; F:DNA-binding transcription factor activity, RNA polymerase II-specific; IBA:GO_Central.
DR   GO; GO:0000977; F:RNA polymerase II transcription regulatory region sequence-specific DNA binding; IBA:GO_Central.
DR   GO; GO:0043565; F:sequence-specific DNA binding; ISS:UniProtKB.
DR   GO; GO:0030154; P:cell differentiation; IEA:UniProtKB-KW.
DR   GO; GO:0001707; P:mesoderm formation; ISS:UniProtKB.
DR   GO; GO:0007399; P:nervous system development; IEA:UniProtKB-KW.
DR   GO; GO:0045893; P:positive regulation of transcription, DNA-templated; ISS:UniProtKB.
DR   GO; GO:0006357; P:regulation of transcription by RNA polymerase II; IBA:GO_Central.
DR   GO; GO:0060062; P:Spemann organizer formation at the dorsal lip of the blastopore; ISS:UniProtKB.
DR   GO; GO:0016055; P:Wnt signaling pathway; IEA:UniProtKB-KW.
DR   CDD; cd00086; homeodomain; 1.
DR   InterPro; IPR009057; Homeobox-like_sf.
DR   InterPro; IPR001356; Homeobox_dom.
DR   Pfam; PF00046; Homeodomain; 1.
DR   SMART; SM00389; HOX; 1.
DR   SUPFAM; SSF46689; SSF46689; 1.
DR   PROSITE; PS50071; HOMEOBOX_2; 1.
PE   2: Evidence at transcript level;
KW   Activator; Developmental protein; Differentiation; DNA-binding;
KW   Gastrulation; Homeobox; Neurogenesis; Nucleus; Reference proteome;
KW   Transcription; Transcription regulation; Wnt signaling pathway.
FT   CHAIN           1..240
FT                   /note="Homeobox protein siamois"
FT                   /id="PRO_0000274550"
FT   DNA_BIND        136..195
FT                   /note="Homeobox"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00108"
FT   REGION          193..240
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   SITE            185
FT                   /note="Determines DNA-binding specificity"
FT                   /evidence="ECO:0000250|UniProtKB:Q91848"
SQ   SEQUENCE   240 AA;  27674 MW;  A4C695E5012B791B CRC64;
     MTCEAEMEQI VSTALTLQED YIKFTPRNPT MACHTEIIGV FHDIHPTVEK NKEAHRDKLV
     LQETLVELYS VLGIPQEPQV GKTMKFEEPE QHRGSARFDP LVNSLQLKRP LYEEERRECK
     RPLVQADEAV AAPSARSRRR TIYSKEQTHF LQNQFDLNPY PDFVNRCRIA KITAIPEPRI
     QVWFQNRRAR HLPRAATSLS PQERKPPGSV GPRSSLCREA QHPEAWSEVL IPSDSQPHPN