ID   MK_XENTR                Reviewed;         142 AA.
AC   Q6P8F3;
DT   05-OCT-2010, integrated into UniProtKB/Swiss-Prot.
DT   05-JUL-2004, sequence version 1.
DT   03-AUG-2022, entry version 92.
DE   RecName: Full=Midkine {ECO:0000250|UniProtKB:P21741, ECO:0000250|UniProtKB:P48530, ECO:0000312|EMBL:AAH61275.1};
DE            Short=MK {ECO:0000250|UniProtKB:P21741, ECO:0000250|UniProtKB:P48530};
DE   Flags: Precursor;
GN   Name=mdk {ECO:0000312|Xenbase:XB-GENE-488502};
OS   Xenopus tropicalis (Western clawed frog) (Silurana tropicalis).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Amphibia;
OC   Batrachia; Anura; Pipoidea; Pipidae; Xenopodinae; Xenopus; Silurana.
OX   NCBI_TaxID=8364;
RN   [1] {ECO:0000312|EMBL:AAH61275.1}
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
RC   TISSUE=Tadpole {ECO:0000312|EMBL:AAH61275.1};
RG   NIH - Xenopus Gene Collection (XGC) project;
RL   Submitted (NOV-2003) to the EMBL/GenBank/DDBJ databases.
CC   -!- FUNCTION: Secreted protein that functions as cytokine and growth factor
CC       and mediates its signal through cell-surface proteoglycan and non-
CC       proteoglycan receptors. Binds cell-surface proteoglycan receptors via
CC       their chondroitin sulfate (CS) groups. Thereby regulates many processes
CC       like inflammatory response, cell proliferation, cell adhesion, cell
CC       growth, cell survival, tissue regeneration, cell differentiation and
CC       cell migration (By similarity). Inhibits mesoderm formation and
CC       promotes neural formation during development. Plays a role in
CC       development of the neuromuscular junction (NMJ). Has antibacterial
CC       activity against both Gram-positive and Gram-negative bacteria (By
CC       similarity). {ECO:0000250|UniProtKB:P21741,
CC       ECO:0000250|UniProtKB:P48530}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250|UniProtKB:P21741}.
CC   -!- SIMILARITY: Belongs to the pleiotrophin family. {ECO:0000255}.
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DR   EMBL; BC061275; AAH61275.1; -; mRNA.
DR   RefSeq; NP_989074.1; NM_203743.1.
DR   AlphaFoldDB; Q6P8F3; -.
DR   SMR; Q6P8F3; -.
DR   STRING; 8364.ENSXETP00000010258; -.
DR   PaxDb; Q6P8F3; -.
DR   DNASU; 394671; -.
DR   GeneID; 394671; -.
DR   KEGG; xtr:394671; -.
DR   CTD; 4192; -.
DR   Xenbase; XB-GENE-488502; mdk.
DR   eggNOG; ENOG502S022; Eukaryota.
DR   HOGENOM; CLU_136864_0_0_1; -.
DR   InParanoid; Q6P8F3; -.
DR   OMA; CASKMKS; -.
DR   OrthoDB; 1489280at2759; -.
DR   PhylomeDB; Q6P8F3; -.
DR   TreeFam; TF332376; -.
DR   Reactome; R-XTR-201556; Signaling by ALK.
DR   Proteomes; UP000008143; Chromosome 4.
DR   Proteomes; UP000790000; Unplaced.
DR   Bgee; ENSXETG00000001967; Expressed in neurula embryo and 12 other tissues.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0008083; F:growth factor activity; IBA:GO_Central.
DR   GO; GO:0043395; F:heparan sulfate proteoglycan binding; ISS:UniProtKB.
DR   GO; GO:0008201; F:heparin binding; ISS:UniProtKB.
DR   GO; GO:0030154; P:cell differentiation; IEA:UniProtKB-KW.
DR   GO; GO:0042742; P:defense response to bacterium; IEA:UniProtKB-KW.
DR   GO; GO:0007399; P:nervous system development; ISS:UniProtKB.
DR   GO; GO:0007528; P:neuromuscular junction development; ISS:UniProtKB.
DR   GO; GO:0051781; P:positive regulation of cell division; IEA:UniProtKB-KW.
DR   GO; GO:0009617; P:response to bacterium; ISS:UniProtKB.
DR   Gene3D; 2.20.60.10; -; 1.
DR   Gene3D; 2.30.90.10; -; 1.
DR   InterPro; IPR000762; Midkine_heparin-bd_GF.
DR   InterPro; IPR020090; PTN/MK_C_dom.
DR   InterPro; IPR038130; PTN/MK_C_dom_sf.
DR   InterPro; IPR020091; PTN/MK_diS_sf.
DR   InterPro; IPR020089; PTN/MK_N_dom.
DR   InterPro; IPR037122; PTN/MK_N_dom_sf.
DR   InterPro; IPR020092; PTN_MK_heparin-bd_GF_CS.
DR   PANTHER; PTHR13850; PTHR13850; 1.
DR   Pfam; PF01091; PTN_MK_C; 1.
DR   Pfam; PF05196; PTN_MK_N; 1.
DR   PRINTS; PR00269; PTNMIDKINE.
DR   SMART; SM00193; PTN; 1.
DR   SUPFAM; SSF57288; SSF57288; 2.
DR   PROSITE; PS00619; PTN_MK_1; 1.
DR   PROSITE; PS00620; PTN_MK_2; 1.
PE   2: Evidence at transcript level;
KW   Antibiotic; Antimicrobial; Developmental protein; Differentiation;
KW   Disulfide bond; Growth factor; Heparin-binding; Mitogen;
KW   Reference proteome; Secreted; Signal.
FT   SIGNAL          1..21
FT                   /evidence="ECO:0000255"
FT   CHAIN           22..142
FT                   /note="Midkine"
FT                   /evidence="ECO:0000255"
FT                   /id="PRO_0000398805"
FT   DISULFID        36..60
FT                   /evidence="ECO:0000250|UniProtKB:P21741"
FT   DISULFID        44..69
FT                   /evidence="ECO:0000250|UniProtKB:P21741"
FT   DISULFID        51..73
FT                   /evidence="ECO:0000250|UniProtKB:P21741"
FT   DISULFID        83..115
FT                   /evidence="ECO:0000250|UniProtKB:P21741"
FT   DISULFID        93..125
FT                   /evidence="ECO:0000250|UniProtKB:P21741"
SQ   SEQUENCE   142 AA;  15684 MW;  4D036A91833899A2 CRC64;
     MELRAFCVIL LITFLAVSSQ AAKNKKEKGK KGASDCTEWT WGRCIPNSKD CGAGTREGTC
     KEETRKLKCK IPCNWKKAFG ADCKYKFENW GECNATTGQK VRSGTLKKAL YNADCQQTVE
     ATKPCSLKTK SKSKGKKGKG KE