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2.A.112.1.13
Xkr8 (XK8, XRG8) is of 395 aas and 6 - 11 apparent TMSs based on hydropathy plots. It catalyzes phosphatidyl serine (PS) flipping from the inner leaflet to the outer leaflet of the cell membrane to signal appoptosis (Sivagnanam et al. 2017).  It has a C-terminal caspase recognition sequence that may play a role in apoptosis signalling. Xkr4 TC# 2.A.112.1.11), Xkr8 and Xkr9 (TC# 2.A.112.1.12) have this activity and have several essential residues in TMS2 and cytoplasmic loop 2 (Suzuki et al. 2014). It is a 6 TMS protein that is activated by caspases during apoptosis and promotes phospholipid scrambling, thus exposing PS as an """"eat-me-signal"""" (Suzuki and Nagata 2014). Basigin (BSG; TC# 2.A.23.1.1) and neuroplastin (NPTN; TC# 2.A.23.1.8)) bind to Xkr8 and usher it to the plasma membrane (Suzuki et al. 2016).

Accession Number:Q9H6D3
Protein Name:XK-related protein 8
Length:395
Molecular Weight:44655.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:9
Location1 / Topology2 / Orientation3: Cell membrane1 / Multi-pass membrane protein2
Substrate phospholipids

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FASTA formatted sequence
1:	MPWSSRGALL RDLVLGVLGT AAFLLDLGTD LWAAVQYALG GRYLWAALVL ALLGLASVAL 
61:	QLFSWLWLRA DPAGLHGSQP PRRCLALLHL LQLGYLYRCV QELRQGLLVW QQEEPSEFDL 
121:	AYADFLALDI SMLRLFETFL ETAPQLTLVL AIMLQSGRAE YYQWVGICTS FLGISWALLD 
181:	YHRALRTCLP SKPLLGLGSS VIYFLWNLLL LWPRVLAVAL FSALFPSYVA LHFLGLWLVL 
241:	LLWVWLQGTD FMPDPSSEWL YRVTVATILY FSWFNVAEGR TRGRAIIHFA FLLSDSILLV 
301:	ATWVTHSSWL PSGIPLQLWL PVGCGCFFLG LALRLVYYHW LHPSCCWKPD PDQVDGARSL 
361:	LSPEGYQLPQ NRRMTHLAQK FFPKAKDEAA SPVKG