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).
|Protein Name:||XK-related protein 8|
|Species:||Homo sapiens (Human)  |
|Number of TMSs:||9|
|Location1 / Topology2 / Orientation3:
Cell membrane1 / Multi-pass membrane protein2
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