ID   CO4_CAVPO               Reviewed;          22 AA.
AC   P19069;
DT   01-NOV-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1990, sequence version 1.
DT   25-MAY-2022, entry version 54.
DE   RecName: Full=Complement C4;
DE   Flags: Fragment;
GN   Name=C4;
OS   Cavia porcellus (Guinea pig).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Euarchontoglires; Glires; Rodentia; Hystricomorpha; Caviidae;
OC   Cavia.
OX   NCBI_TaxID=10141;
RN   [1]
RP   PROTEIN SEQUENCE.
RX   PubMed=7391069; DOI=10.1016/s0021-9258(20)79661-4;
RA   Goldberger G., Abraham G.N., Williams J., Colten H.R.;
RT   "NH2-terminal sequence analysis of pro-C4, the precursor of the fourth
RT   component of guinea pig complement.";
RL   J. Biol. Chem. 255:7071-7074(1980).
CC   -!- FUNCTION: Non-enzymatic component of C3 and C5 convertases and thus
CC       essential for the propagation of the classical complement pathway.
CC       Covalently binds to immunoglobulins and immune complexes and enhances
CC       the solubilization of immune aggregates and the clearance of IC through
CC       CR1 on erythrocytes (By similarity). {ECO:0000250}.
CC   -!- SUBUNIT: This protein is synthesized as a single-chain precursor and,
CC       prior to secretion, is enzymatically cleaved to form a trimer of non-
CC       identical chains alpha, beta and gamma.
CC   -!- SUBCELLULAR LOCATION: Secreted.
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DR   PIR; A17267; A17267.
DR   Proteomes; UP000005447; Unassembled WGS sequence.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0006958; P:complement activation, classical pathway; IEA:UniProtKB-KW.
DR   GO; GO:0006954; P:inflammatory response; IEA:UniProtKB-KW.
DR   GO; GO:0045087; P:innate immune response; IEA:UniProtKB-KW.
PE   1: Evidence at protein level;
KW   Complement pathway; Direct protein sequencing; Immunity;
KW   Inflammatory response; Innate immunity; Reference proteome; Secreted.
FT   CHAIN           1..>22
FT                   /note="Complement C4"
FT                   /id="PRO_0000048519"
FT   VARIANT         18
FT                   /note="L -> V"
FT   NON_TER         22
SQ   SEQUENCE   22 AA;  2458 MW;  2CD16B54D0BB47A4 CRC64;
     KPRLLLFXPX VVVLXVPLXV XV