ID   B3_USTMD                Reviewed;         410 AA.
AC   P22017;
DT   01-AUG-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1991, sequence version 1.
DT   25-MAY-2022, entry version 90.
DE   RecName: Full=Mating-type locus allele B3 protein;
OS   Ustilago maydis (Corn smut fungus).
OC   Eukaryota; Fungi; Dikarya; Basidiomycota; Ustilaginomycotina;
OC   Ustilaginomycetes; Ustilaginales; Ustilaginaceae; Ustilago.
OX   NCBI_TaxID=5270;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=RK32;
RX   PubMed=1967554; DOI=10.1016/0092-8674(90)90744-y;
RA   Schulz B., Banuett F., Dahl M., Schlesinger R., Schaefer W., Martin T.,
RA   Herskowitz I., Kahmann R.;
RT   "The b alleles of U. maydis, whose combinations program pathogenic
RT   development, code for polypeptides containing a homeodomain-related
RT   motif.";
RL   Cell 60:295-306(1990).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 18604;
RX   PubMed=2227416; DOI=10.1101/gad.4.8.1384;
RA   Kronstad J.W., Leong S.A.;
RT   "The b mating-type locus of Ustilago maydis contains variable and constant
RT   regions.";
RL   Genes Dev. 4:1384-1395(1990).
CC   -!- FUNCTION: The B locus has at least 25 alleles, and any combination of
CC       two different B alleles yields a multimeric regulatory protein, that
CC       activates genes responsible for the pathogenicity and for the sexual
CC       development of the fungus within the corn plant.
CC   -!- SUBCELLULAR LOCATION: Nucleus.
CC   -!- SIMILARITY: Belongs to the TALE/M-ATYP homeobox family. {ECO:0000305}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   EMBL; M58555; AAA63555.1; -; Genomic_DNA.
DR   PIR; C36671; C36671.
DR   PIR; D32696; D32696.
DR   AlphaFoldDB; P22017; -.
DR   SMR; P22017; -.
DR   VEuPathDB; FungiDB:UMAG_12052; -.
DR   GO; GO:0005634; C:nucleus; IEA:UniProtKB-SubCell.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0006355; P:regulation of transcription, DNA-templated; IEA:InterPro.
DR   CDD; cd00086; homeodomain; 1.
DR   InterPro; IPR009057; Homeobox-like_sf.
DR   InterPro; IPR001356; Homeobox_dom.
DR   InterPro; IPR008422; Homeobox_KN_domain.
DR   InterPro; IPR008888; Ustilago_mating.
DR   Pfam; PF05920; Homeobox_KN; 1.
DR   Pfam; PF05722; Ustilago_mating; 1.
DR   SUPFAM; SSF46689; SSF46689; 1.
DR   PROSITE; PS50071; HOMEOBOX_2; 1.
PE   3: Inferred from homology;
KW   DNA-binding; Homeobox; Nucleus.
FT   CHAIN           1..410
FT                   /note="Mating-type locus allele B3 protein"
FT                   /id="PRO_0000049403"
FT   DNA_BIND        107..184
FT                   /note="Homeobox; TALE-type"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00108"
FT   REGION          1..110
FT                   /note="Variable domain between B alleles"
FT   REGION          111..410
FT                   /note="Highly conserved between B alleles"
FT   REGION          203..224
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   REGION          278..335
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   REGION          333..410
FT                   /note="Not essential for B3 function"
FT   MOTIF           276..308
FT                   /note="Nuclear localization signal"
FT                   /evidence="ECO:0000255"
FT   COMPBIAS        203..219
FT                   /note="Polar residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        309..335
FT                   /note="Polar residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
SQ   SEQUENCE   410 AA;  46323 MW;  6E8D31DF116EA94E CRC64;
     MSRDPKLSLS KFLECLNEIE HEFLRDKVEH RPVLVRKLQE LQQKTPKHVA KLPHEPEMIQ
     QIHQAAHRID IVAQAFIRFD QKFVSLCSEI VHDTTKVMQE ANVVSPGEGC RNLSEDLPAY
     HMRNHFLHTL ENPYPTQEEK EGLVRLTNES TARIRPSNAI RPPLEVHQLT LWFINARRRS
     GWSHILKKFA REDPSRMKRL VRAKLSSSNQ STPPSLTSEK PSDDLDVVLS DNLGRPLTLA
     DKQQFEDDWA SMISWIKYGV KEKVGDWVYD LCAASKKTPK PGMPRPVTTV AKRHPARKTK
     PAAKPKSRTA NPRASTTPSI DSTLDSSKLE STPELSMCST ADTSFSTFGS SLSMSHYNPF
     QDGNDILQSP TVKARGNRKV KALPKRAGKQ QPDEVDNGKI PFLCLSVAFV