ID   RPC3_BPHK0              Reviewed;          44 AA.
AC   P18681;
DT   01-NOV-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1990, sequence version 1.
DT   23-FEB-2022, entry version 67.
DE   RecName: Full=Regulatory protein CIII;
GN   Name=CIII;
OS   Escherichia phage HK022 (Bacteriophage HK022).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Siphoviridae; Hendrixvirinae; Shamshuipovirus.
OX   NCBI_TaxID=10742;
OH   NCBI_TaxID=562; Escherichia coli.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=2760929; DOI=10.1016/0022-2836(89)90237-4;
RA   Oberto J., Weisberg R.A., Gottesman M.E.;
RT   "Structure and function of the nun gene and the immunity region of the
RT   lambdoid phage HK022.";
RL   J. Mol. Biol. 207:675-693(1989).
RN   [2]
RP   MUTAGENESIS.
RX   PubMed=1828895; DOI=10.1073/pnas.88.12.5217;
RA   Kornitzer D., Altuvia S., Oppenheim A.B.;
RT   "The activity of the CIII regulator of lambdoid bacteriophages resides
RT   within a 24-amino acid protein domain.";
RL   Proc. Natl. Acad. Sci. U.S.A. 88:5217-5221(1991).
CC   -!- FUNCTION: Presence of the CIII protein in the cell results in the
CC       stabilization of the CII transcriptional activator (a very unstable
CC       protein), CII activates CI, the gene for repressor, and thus promotes
CC       the establishment of lysogeny.
CC   -!- SIMILARITY: Belongs to the lambda phage CIII protein family.
CC       {ECO:0000305}.
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DR   EMBL; X16093; CAA34220.1; -; Genomic_DNA.
DR   PIR; S06538; QCBPHK.
DR   InterPro; IPR012995; CIII_regul.
DR   InterPro; IPR013056; Phage_lambda_CIII.
DR   Pfam; PF08134; cIII; 1.
DR   PROSITE; PS00553; LAMBDA_PHAGE_CIII; 1.
PE   1: Evidence at protein level;
KW   Activator; Transcription; Transcription regulation.
FT   CHAIN           1..44
FT                   /note="Regulatory protein CIII"
FT                   /id="PRO_0000077594"
FT   MUTAGEN         20
FT                   /note="S->F: Low CIII activity."
FT                   /evidence="ECO:0000269|PubMed:1828895"
FT   MUTAGEN         21
FT                   /note="E->K: Low CIII activity."
FT                   /evidence="ECO:0000269|PubMed:1828895"
FT   MUTAGEN         24
FT                   /note="R->H: Low CIII activity."
FT                   /evidence="ECO:0000269|PubMed:1828895"
SQ   SEQUENCE   44 AA;  4994 MW;  22A109AE50EDF66F CRC64;
     MMHFQLAGSG VMSAFYPHES ELSRRVKQLI RAAKKQLEAL CAMK