ID   PORTL_BPLSK             Reviewed;         378 AA.
AC   O21872;
DT   02-NOV-2016, integrated into UniProtKB/Swiss-Prot.
DT   01-JAN-1998, sequence version 1.
DT   12-AUG-2020, entry version 44.
DE   RecName: Full=Probable portal protein {ECO:0000250|UniProtKB:D3WAC3};
DE   AltName: Full=Gene product 4 {ECO:0000305};
DE            Short=gp4 {ECO:0000305};
DE   AltName: Full=Putative portal protein {ECO:0000250|UniProtKB:D3WAC3};
OS   Lactococcus phage SK1 (Lactococcus lactis bacteriophage SK1).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Siphoviridae; Skunavirus.
OX   NCBI_TaxID=31532;
OH   NCBI_TaxID=1358; Lactococcus lactis.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RX   PubMed=9383189; DOI=10.1046/j.1365-2958.1997.5491926.x;
RA   Chandry P.S., Moore S.C., Boyce J.D., Davidson B.E., Hillier A.J.;
RT   "Analysis of the DNA sequence, gene expression, origin of replication and
RT   modular structure of the Lactococcus lactis lytic bacteriophage sk1.";
RL   Mol. Microbiol. 26:49-64(1997).
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       Necessary to ensure correct procapsid size during capsid assembly. Once
CC       the capsid is packaged with the DNA, the terminase complex is
CC       substituted by the connector proteins gp15.
CC       {ECO:0000250|UniProtKB:D3WAC3}.
CC   -!- SUBUNIT: Homododecamer. {ECO:0000250|UniProtKB:D3WAC3}.
CC   -!- SUBCELLULAR LOCATION: Virion {ECO:0000250|UniProtKB:D3WAC3}.
CC       Note=Occupies the twelfth vertex of the capsid.
CC       {ECO:0000250|UniProtKB:D3WAC3}.
CC   -!- SIMILARITY: Belongs to the skunalikevirus portal protein family.
CC       {ECO:0000305}.
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DR   EMBL; AF011378; AAB70043.1; -; Genomic_DNA.
DR   RefSeq; NP_044950.1; NC_001835.1.
DR   GeneID; 1261302; -.
DR   KEGG; vg:1261302; -.
DR   Proteomes; UP000000839; Genome.
DR   GO; GO:0019028; C:viral capsid; IEA:UniProtKB-KW.
DR   GO; GO:0099001; P:viral genome ejection through host cell envelope, long flexible tail mechanism; IEA:UniProtKB-KW.
DR   InterPro; IPR006944; Phage/GTA_portal.
DR   Pfam; PF04860; Phage_portal; 1.
PE   3: Inferred from homology;
KW   Capsid protein; Reference proteome; 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..378
FT                   /note="Probable portal protein"
FT                   /id="PRO_0000438252"
SQ   SEQUENCE   378 AA;  43276 MW;  76FA9700DB766B7D CRC64;
     MNLFGKVVSF SRGKLNNDTQ RVTAWQNEAV EYTSAFVTNI HNKIANEITK VEFNHVKYKK
     SDVGSDTLIS MAGSDLDEVL NWSPKGERNS MDFWRKVIKK LLRAPYVDLY AVFDDNTGEL
     LDLLFADDKK EYKPEELVRL TSPFYINEDT SILDNALASI QTKLEQGKLR GLLKINAFLD
     IDNTQEYREK ALTTIKNMQE GSSYNGLTPV DNKTEIVELK KDYSVLNKDE IDLIKSELLT
     GYFMNENILL GTASQEQQIY FYNSTIIPLL IQLEKELTYK LISTNRRRVV KGNLYYERII
     VDNQLFKFAT LKELIDLYHE NINGPIFTQN QLLVKMGEQP IEGGDVYIAN LNAVAVKNLS
     DLQGSRKDVT STDETNNQ