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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.  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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Predict TMSs (Predict number of transmembrane segments)
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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