ID   W_BPP21                 Reviewed;          68 AA.
AC   P68656; P36271;
DT   07-DEC-2004, integrated into UniProtKB/Swiss-Prot.
DT   07-DEC-2004, sequence version 1.
DT   29-SEP-2021, entry version 49.
DE   RecName: Full=Head completion protein gp3;
DE   AltName: Full=Gene product 3;
DE            Short=gp3;
DE   AltName: Full=Head-stabilizing protein;
DE   AltName: Full=Head-tail joining protein;
GN   Name=3;
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: Plays a role in morphogenesis of the virion head after genome
CC       packaging. Presumably interacts with the portal vertex to stabilize the
CC       packaged DNA within the head after packaging. Probably binds to the
CC       head-tail connector protein gp8. {ECO:0000250|UniProtKB:P68660}.
CC   -!- SUBUNIT: Monomer in solution, assembles into hexamers on the prohead.
CC       May bind gp8 and portal protein (Potential).
CC       {ECO:0000250|UniProtKB:P68660}.
CC   -!- SUBCELLULAR LOCATION: Virion {ECO:0000250|UniProtKB:P68660}.
CC       Note=Probably part of the head-tail connector.
CC       {ECO:0000250|UniProtKB:P68660}.
CC   -!- SIMILARITY: Belongs to the lambda phage gpW family. {ECO:0000305}.
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DR   EMBL; M81255; AAA32341.1; -; Genomic_DNA.
DR   PIR; JN0537; JN0537.
DR   SMR; P68656; -.
DR   GO; GO:0019058; P:viral life cycle; IEA:InterPro.
DR   Gene3D; 3.30.1580.10; -; 1.
DR   InterPro; IPR004174; GpW.
DR   InterPro; IPR036626; GpW_sf.
DR   Pfam; PF02831; gpW; 1.
DR   SUPFAM; SSF64210; SSF64210; 1.
PE   3: Inferred from homology;
KW   Late protein; Viral capsid assembly; Viral release from host cell; Virion.
FT   CHAIN           1..68
FT                   /note="Head completion protein gp3"
FT                   /id="PRO_0000077648"
SQ   SEQUENCE   68 AA;  7621 MW;  54F7BCD9CEA1F2F4 CRC64;
     MVTVAELQAL RQARLDLLTG KRVVSVQKDG RRIEYTAASL DELNRAINDA ESVLGTTRCR
     RRPLGVRL