ID   XKR8_PANTR              Reviewed;         395 AA.
AC   Q49LS0;
DT   11-OCT-2005, integrated into UniProtKB/Swiss-Prot.
DT   13-SEP-2005, sequence version 1.
DT   25-MAY-2022, entry version 58.
DE   RecName: Full=XK-related protein 8 {ECO:0000305};
DE   Contains:
DE     RecName: Full=XK-related protein 8, processed form {ECO:0000250|UniProtKB:Q9H6D3};
GN   Name=XKR8 {ECO:0000250|UniProtKB:Q9H6D3};
GN   Synonyms=XRG8 {ECO:0000303|Ref.1};
OS   Pan troglodytes (Chimpanzee).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae;
OC   Pan.
OX   NCBI_TaxID=9598;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RA   Huang C.-H., Chen Y.;
RT   "A superfamily of XK-related genes (XRG) widely expressed in vertebrates
RT   and invertebrates.";
RL   Submitted (JUL-2004) to the EMBL/GenBank/DDBJ databases.
CC   -!- FUNCTION: [XK-related protein 8, processed form]: Phospholipid
CC       scramblase that promotes phosphatidylserine exposure on apoptotic cell
CC       surface. Phosphatidylserine is a specific marker only present at the
CC       surface of apoptotic cells and acts as a specific signal for
CC       engulfment. Required for the clearance of apoptotic cells, such as
CC       engulfment of apoptotic germ cells by Sertoli cells, clearance of
CC       senescent neutrophils or regulation of bipolar cell numbers in the
CC       retina (By similarity). Has no effect on calcium-induced exposure of
CC       phosphatidylserine (By similarity). Promotes myoblast differentiation
CC       and survival (By similarity). {ECO:0000250|UniProtKB:Q8C0T0,
CC       ECO:0000250|UniProtKB:Q9H6D3}.
CC   -!- CATALYTIC ACTIVITY: [XK-related protein 8, processed form]:
CC       Reaction=a 1,2-diacyl-sn-glycero-3-phospho-L-serine(in) = a 1,2-diacyl-
CC         sn-glycero-3-phospho-L-serine(out); Xref=Rhea:RHEA:38663,
CC         ChEBI:CHEBI:57262; Evidence={ECO:0000250|UniProtKB:Q8C0T0};
CC   -!- ACTIVITY REGULATION: Activated upon caspase cleavage to generate the
CC       XK-related protein 8, processed form. Does not act prior the onset of
CC       apoptosis. {ECO:0000250|UniProtKB:Q9H6D3}.
CC   -!- SUBUNIT: Interacts with BSG and NPTN; which act as chaperones to
CC       localize XKR8 at the cell membrane. {ECO:0000250|UniProtKB:Q8C0T0}.
CC   -!- SUBUNIT: [XK-related protein 8, processed form]: Homodimer.
CC       {ECO:0000250|UniProtKB:Q9H6D3}.
CC   -!- SUBCELLULAR LOCATION: Cell membrane {ECO:0000250|UniProtKB:Q8C0T0};
CC       Multi-pass membrane protein {ECO:0000255}. Cytoplasm, perinuclear
CC       region {ECO:0000250|UniProtKB:Q9H6D3}.
CC   -!- PTM: Undergoes proteolytic processing by caspase-3 (CASP3), leading to
CC       its activation. {ECO:0000250|UniProtKB:Q8C0T0}.
CC   -!- PTM: Phosphorylation at Thr-375 activates the phospholipid scramblase
CC       activity. {ECO:0000250|UniProtKB:Q8C0T0}.
CC   -!- SIMILARITY: Belongs to the XK family. {ECO:0000305}.
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DR   EMBL; AY702911; AAV83784.1; -; mRNA.
DR   RefSeq; NP_001028209.1; NM_001033037.1.
DR   AlphaFoldDB; Q49LS0; -.
DR   SMR; Q49LS0; -.
DR   STRING; 9598.ENSPTRP00000054182; -.
DR   PaxDb; Q49LS0; -.
DR   GeneID; 613218; -.
DR   KEGG; ptr:613218; -.
DR   CTD; 55113; -.
DR   eggNOG; KOG4790; Eukaryota.
DR   InParanoid; Q49LS0; -.
DR   OrthoDB; 1230316at2759; -.
DR   Proteomes; UP000002277; Unplaced.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0048471; C:perinuclear region of cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0005886; C:plasma membrane; ISS:UniProtKB.
DR   GO; GO:0017128; F:phospholipid scramblase activity; ISS:UniProtKB.
DR   GO; GO:0043652; P:engulfment of apoptotic cell; ISS:UniProtKB.
DR   GO; GO:0097350; P:neutrophil clearance; ISS:UniProtKB.
DR   GO; GO:0070782; P:phosphatidylserine exposure on apoptotic cell surface; ISS:UniProtKB.
DR   GO; GO:0045663; P:positive regulation of myoblast differentiation; ISS:UniProtKB.
DR   InterPro; IPR018629; XK-rel.
DR   Pfam; PF09815; XK-related; 1.
PE   2: Evidence at transcript level;
KW   Apoptosis; Cell membrane; Cytoplasm; Membrane; Phosphoprotein;
KW   Reference proteome; Transmembrane; Transmembrane helix.
FT   CHAIN           1..395
FT                   /note="XK-related protein 8"
FT                   /id="PRO_0000190793"
FT   CHAIN           1..355
FT                   /note="XK-related protein 8, processed form"
FT                   /evidence="ECO:0000250|UniProtKB:Q9H6D3"
FT                   /id="PRO_0000423986"
FT   TOPO_DOM        1..12
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        13..33
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        34..47
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        48..68
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        69..158
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        159..179
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        180..200
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        201..221
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        222..223
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        224..244
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        245..258
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        259..279
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        280..284
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        285..305
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        306..312
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        313..333
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        334..395
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   SITE            355..356
FT                   /note="Cleavage; by caspase-3"
FT                   /evidence="ECO:0000250|UniProtKB:Q9H6D3"
FT   MOD_RES         362
FT                   /note="Phosphoserine"
FT                   /evidence="ECO:0000250|UniProtKB:Q8C0T0"
FT   MOD_RES         375
FT                   /note="Phosphothreonine"
FT                   /evidence="ECO:0000250|UniProtKB:Q8C0T0"
SQ   SEQUENCE   395 AA;  44667 MW;  A76779175238E38A CRC64;
     MPWSSRGALL RDLVLGVLGT AAFLLDLGTD LWAAVQYALG GRYLWAALVL ALLGLASVAL
     QLFSWLWLRA DPAGLHGSQP PRRCLALLHL LQLGYLYRCV QELRQGLLVW QQEEPSEFDL
     AYADFLALDI SMLRLFETFL ETAPQLTLVL AIMLQSGRAE YYQWVGICTS FLGISWALLD
     YHRALRTCLP SRPLLGLGSS VIYFLWNLLL LWPRVLAVAL FSALFPSYVA LHFLGLWLVL
     LLWVWLQGTD FMPDPSSEWL YQVTVATILY FSWFNVAEGR TRGRAIIHFA FLLSDSILLV
     ATWVTHSSWL PSGIPLQLWL PVGCGCFFLG LALRLVYYHW LHPSCCWKPD PDQVDGARSL
     LSPEGYQLPQ NRRMTHLAQN FFPKAKDEAA LPVKG