ID   IL2_HORSE               Reviewed;         149 AA.
AC   P37997;
DT   01-OCT-1994, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1995, sequence version 2.
DT   03-AUG-2022, entry version 112.
DE   RecName: Full=Interleukin-2;
DE            Short=IL-2;
DE   AltName: Full=T-cell growth factor;
DE            Short=TCGF;
DE   Flags: Precursor;
GN   Name=IL2;
OS   Equus caballus (Horse).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Perissodactyla; Equidae; Equus.
OX   NCBI_TaxID=9796;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=8508756; DOI=10.1111/j.2042-3306.1993.tb02953.x;
RA   Tavernor A.S., Allen W.R., Butcher G.W.;
RT   "cDNA cloning of equine interleukin-2 by polymerase chain reaction.";
RL   Equine Vet. J. 25:242-243(1993).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=8116217; DOI=10.1016/0165-2427(93)90070-k;
RA   Vandergrifft E.V., Horohov D.W.;
RT   "Molecular cloning and expression of equine interleukin 2.";
RL   Vet. Immunol. Immunopathol. 39:395-406(1993).
CC   -!- FUNCTION: Cytokine produced by activated CD4-positive helper T-cells
CC       and to a lesser extend activated CD8-positive T-cells and natural
CC       killer (NK) cells that plays pivotal roles in the immune response and
CC       tolerance. Binds to a receptor complex composed of either the high-
CC       affinity trimeric IL-2R (IL2RA/CD25, IL2RB/CD122 and IL2RG/CD132) or
CC       the low-affinity dimeric IL-2R (IL2RB and IL2RG). Interaction with the
CC       receptor leads to oligomerization and conformation changes in the IL-2R
CC       subunits resulting in downstream signaling starting with
CC       phosphorylation of JAK1 and JAK3. In turn, JAK1 and JAK3 phosphorylate
CC       the receptor to form a docking site leading to the phosphorylation of
CC       several substrates including STAT5. This process leads to activation of
CC       several pathways including STAT, phosphoinositide-3-kinase/PI3K and
CC       mitogen-activated protein kinase/MAPK pathways. Functions as a T-cell
CC       growth factor and can increase NK-cell cytolytic activity as well.
CC       Promotes strong proliferation of activated B-cells and subsequently
CC       immunoglobulin production. Plays a pivotal role in regulating the
CC       adaptive immune system by controlling the survival and proliferation of
CC       regulatory T-cells, which are required for the maintenance of immune
CC       tolerance. Moreover, participates in the differentiation and
CC       homeostasis of effector T-cell subsets, including Th1, Th2, Th17 as
CC       well as memory CD8-positive T-cells. {ECO:0000250|UniProtKB:P60568}.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- SIMILARITY: Belongs to the IL-2 family. {ECO:0000305}.
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DR   EMBL; X69393; CAA49190.1; -; mRNA.
DR   EMBL; L06009; AAA20134.1; -; mRNA.
DR   PIR; S31391; S31391.
DR   RefSeq; NP_001078902.1; NM_001085433.2.
DR   AlphaFoldDB; P37997; -.
DR   SMR; P37997; -.
DR   STRING; 9796.ENSECAP00000013353; -.
DR   PaxDb; P37997; -.
DR   GeneID; 100034204; -.
DR   KEGG; ecb:100034204; -.
DR   CTD; 3558; -.
DR   InParanoid; P37997; -.
DR   OrthoDB; 1491449at2759; -.
DR   Proteomes; UP000002281; Unplaced.
DR   GO; GO:0005615; C:extracellular space; IEA:UniProtKB-KW.
DR   GO; GO:0005125; F:cytokine activity; IEA:UniProtKB-KW.
DR   GO; GO:0008083; F:growth factor activity; IEA:UniProtKB-KW.
DR   GO; GO:0005134; F:interleukin-2 receptor binding; IEA:InterPro.
DR   GO; GO:0002250; P:adaptive immune response; IEA:UniProtKB-KW.
DR   Gene3D; 1.20.1250.10; -; 1.
DR   InterPro; IPR009079; 4_helix_cytokine-like_core.
DR   InterPro; IPR000779; IL-2.
DR   InterPro; IPR030477; IL-2_CS.
DR   Pfam; PF00715; IL2; 1.
DR   PRINTS; PR00265; INTERLEUKIN2.
DR   SMART; SM00189; IL2; 1.
DR   SUPFAM; SSF47266; SSF47266; 1.
DR   PROSITE; PS00424; INTERLEUKIN_2; 1.
PE   2: Evidence at transcript level;
KW   Adaptive immunity; Cytokine; Disulfide bond; Glycoprotein; Growth factor;
KW   Immunity; Reference proteome; Secreted; Signal.
FT   SIGNAL          1..20
FT                   /evidence="ECO:0000250"
FT   CHAIN           21..149
FT                   /note="Interleukin-2"
FT                   /id="PRO_0000015483"
FT   CARBOHYD        23
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000250"
FT   CARBOHYD        106
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   DISULFID        78..121
FT                   /evidence="ECO:0000250"
FT   CONFLICT        3
FT                   /note="R -> K (in Ref. 2; CAA49190)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        8
FT                   /note="S -> A (in Ref. 2; CAA49190)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        59
FT                   /note="I -> M (in Ref. 2; CAA49190)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        125
FT                   /note="N -> D (in Ref. 2; CAA49190)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        128
FT                   /note="E -> G (in Ref. 2; CAA49190)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        145
FT                   /note="I -> F (in Ref. 2; CAA49190)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        148
FT                   /note="L -> M (in Ref. 2; CAA49190)"
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   149 AA;  17086 MW;  051BB8C47A0114FC CRC64;
     MYRMQLLSCI ALTLAVLANS APTSSSKRET QQQLKQLQMD LKLLLEGVNN NKNPKLSKIL
     TFKINMPKKA TELKHLQCLE EELKPLEEML KNFLSKDIKE LMSNINVTVL GLKGSETRFT
     CEYDNETETI VEFLNKWITF CQSIISTLT