ID   PORTL_BPP21             Reviewed;         530 AA.
AC   P36272;
DT   01-JUN-1994, integrated into UniProtKB/Swiss-Prot.
DT   01-JUN-1994, sequence version 1.
DT   23-FEB-2022, entry version 69.
DE   RecName: Full=Portal protein B {ECO:0000255|HAMAP-Rule:MF_04135};
DE   AltName: Full=GpB {ECO:0000255|HAMAP-Rule:MF_04135};
DE   AltName: Full=Minor capsid protein B {ECO:0000255|HAMAP-Rule:MF_04135};
GN   Name=B {ECO:0000255|HAMAP-Rule:MF_04135}; Synonyms=4;
OS   Enterobacteria phage P21 (Bacteriophage 21) (Bacteriophage P21).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Siphoviridae; Lambdavirus.
OX   NCBI_TaxID=10711;
OH   NCBI_TaxID=562; Escherichia coli.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=8472949; DOI=10.1016/0378-1119(93)90583-o;
RA   Smith M.P., Feiss M.;
RT   "Sequence analysis of the phage 21 genes for prohead assembly and head
RT   completion.";
RL   Gene 126:1-7(1993).
CC   -!- FUNCTION: Forms the portal vertex of the capsid. This portal plays
CC       critical roles in head assembly, genome packaging, neck/tail
CC       attachment, and genome ejection. The portal protein multimerizes as a
CC       single ring-shaped homododecamer arranged around a central channel.
CC       Binds to the terminase subunits to form the packaging machine.
CC       {ECO:0000255|HAMAP-Rule:MF_04135}.
CC   -!- SUBUNIT: Homododecamer. Interacts with the terminase complex composed
CC       of two small and one large terminase subunits. {ECO:0000255|HAMAP-
CC       Rule:MF_04135}.
CC   -!- SUBCELLULAR LOCATION: Virion {ECO:0000255|HAMAP-Rule:MF_04135}.
CC   -!- PTM: Proteolytically cleaved by the viral protease during capsid
CC       maturation. {ECO:0000255|HAMAP-Rule:MF_04135}.
CC   -!- SIMILARITY: Belongs to the siphoviridae portal protein family.
CC       {ECO:0000255|HAMAP-Rule:MF_04135}.
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DR   EMBL; M81255; AAA32342.1; -; Genomic_DNA.
DR   SMR; P36272; -.
DR   GO; GO:0046798; C:viral portal complex; IEA:UniProtKB-UniRule.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0005198; F:structural molecule activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0099001; P:viral genome ejection through host cell envelope, long flexible tail mechanism; IEA:UniProtKB-UniRule.
DR   GO; GO:0019068; P:virion assembly; IEA:UniProtKB-UniRule.
DR   HAMAP; MF_04135; PORTAL_LAMBDA; 1.
DR   InterPro; IPR006429; Phage_lambda_portal.
DR   Pfam; PF05136; Phage_portal_2; 1.
DR   TIGRFAMs; TIGR01539; portal_lambda; 1.
PE   3: Inferred from homology;
KW   Capsid protein; DNA-binding; Viral capsid assembly;
KW   Viral genome ejection through host cell envelope; Viral genome packaging;
KW   Viral long flexible tail ejection system;
KW   Viral penetration into host cytoplasm; Viral release from host cell;
KW   Virion; Virus entry into host cell.
FT   CHAIN           1..530
FT                   /note="Portal protein B"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04135"
FT                   /id="PRO_0000077658"
SQ   SEQUENCE   530 AA;  59728 MW;  4155924087832F86 CRC64;
     MKRTPVLIDV NGVPLRESLS YNGGGAGFGG QMAEWLPPAQ SADAALLPAL RLGNARADDL
     VRNNGIAANA VALHKDHIVG HMFLISYRPN WRWLGMRETA AKSFVDEVEA AWSEYAEGMF
     GEIDVEGKRT FTEFIREGVG VHAFNGEIFV QPVWDTETTQ LFRTRFKAVS PKRVDTPGHG
     MGNRFLRAGV EVDRYGRAVA YHICEDDFPF SGSGRWERIP RELPTGRPAM LHIFEPVEDG
     QTRGANQFYS VMERLKMLDS LQATQLQSAI VKAMYAATIE SELDTEKAFE YIAGAPQEQK
     DNPLINILEK FSSWYDTNNV TLGGVKIPHL FPGDDLKLQT AQDSDNGFSA LEQALLRYIA
     AGLGVSYEQL SRDYSKVSYS SARASANESW RYFMGRRKFI AARLATQMFS CWLEEALLRG
     IIRPPRARFD FYQARSAWSR AEWIGAGRMA IDGLKEVQES VMRIEAGLST YEKGLALMGE
     DYQDIFRQQV RESAERQKAG LSRPVWIEQA YQQQIAESRR PEEETTPRET