TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
*2.A.112.1.1









The human KX blood group antigen (putative amino acid transporter), KX antigen (Suzuki et al. 2013).

Eukaryota
Metazoa
The KX blood group antigen of Homo sapiens
*2.A.112.1.2









Cell death abnormality protein 8; phospholipid flippase (in to out) (Suzuki et al. 2013; Chen et al. 2013).

Eukaryota
Metazoa
ced-8 of Caenorhabditis elegans
*2.A.112.1.3









The X Kell blood group precursor-related family member 8 homologue isoform CRAa of 401 aas (XK-related protein 8 or XkR8) (Suzuki et al. 2013).

Eukaryota
Metazoa
XkR8 of Mus musculus
*2.A.112.1.4









Uncharacterized protein of 374 aas and ~ 10 TMSs

Eukaryota
Metazoa
UP of Culex quinquefasciatus (Southern house mosquito) (Culex pungens)
*2.A.112.1.5









XkR8 homologue of 352 aas and 8 - 10 TMSs.

Eukaryota
Metazoa
XkR8 homologue of Drosophila melanogaster
*2.A.112.1.6









The XK-related protein 2, XKP2 of 440 aas (Calenda et al. 2006).

Eukaryota
Metazoa
XKP2 of Homo sapiens
*2.A.112.1.7









The XK-related protein 3, XKR3; XRG3, XTES of 459 aas (Calenda et al. 2006).

Eukaryota
Metazoa
XKR3 of Homo sapiens
*2.A.112.1.8









XK protein 6 of 675 aas

Eukaryota
Metazoa
XK protein of Hymenolepis microstoma (Rodent tapeworm) (Rodentolepis microstoma)
*2.A.112.1.9









Uncharacterized protein of 470 aas

Eukaryota
Metazoa
UP of Branchiostoma floridae (Florida lancelet) (Amphioxus)
*2.A.112.1.10









Uncharacterized XK-related protein of 450 aas

Eukaryota
Metazoa
UP of Daphnia pulex (water flea)
*2.A.112.1.11









Xkr4 of 650 aas.  Catalyzes phosphatidyl serine flipping from the inner leaflet to the outer leaflet of the cell membrane to signal appoptosis.  It has a C-terminal caspase recognition signal that may play an important role.  Xkr4, 8 and 9 have this activity and have several essential residues in TMS2 and cytoplasmic loop 2 (Suzuki et al. 2014).

Eukaryota
Metazoa
Xkr4 of Homo sapiens
*2.A.112.1.12









Xkr9 of 650 aas.  Catalyzes phosphatidyl serine flipping from the inner leaflet to the outer leaflet of the cell membrane to signal appoptosis.  It has a C-terminal caspase recognition signal that may play an important role.  Xkr4, 8 and 9 have this activity and have several essential residues in TMS2 and cytoplasmic loop 2 (Suzuki et al. 2014).

Eukaryota
Metazoa
Xkr9 of Homo sapiens
*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).

Eukaryota
Metazoa
Xkr8 of Homo sapiens
*2.A.112.1.14









XKR5 of 686 aas and 5 or 6 TMSs

Eukaryota
Metazoa
XKR5 of Homo sapiens
*2.A.112.1.15









XK-related protein of 603 aas and 8 TMSs.

Eukaryota
Metazoa
XK-protein of Capitella teleta (Polychaete worm)
*2.A.112.1.16









XK-like protein of 667 aas and 9 TMSs

Eukaryota
Metazoa
XK-like protein of Ciona intestinalis (Transparent sea squirt) (Ascidia intestinalis)
*2.A.112.1.17









XK8 or XraB of 404 aas and 9 TMSs

Eukaryota
Metazoa
XK8 of Ciona intestinalis (Transparent sea squirt) (Ascidia intestinalis)
*2.A.112.2.1









XkR8 homologue of 884 aas and 8 - 10 TMSs.

Eukaryota
Viridiplantae
XkR8 homologue of Otreococcus lucimarinus
*2.A.112.2.2









Uncharacterized protein of 1119 aas and 10 TMSs.

Eukaryota
Viridiplantae
UP of Bathycoccus prasinos
*2.A.112.2.3









Uncharacterized protein of 781 aas and 9 TMSs

Eukaryota
Viridiplantae
UP of Coccomyxa subellipsoidea
*2.A.112.2.4









Unchracterized protein of 892 aas

Eukaryota
Viridiplantae
UP of Ostriococcus tauri
*2.A.112.4.1









Uncharacterized protein of 652 aas and 8 TMSs

Eukaryota
Metazoa
UP of Drosophila grimshawi (Fruit fly) (Idiomyia grimshawi)
*2.A.112.4.2









Uncharacterized protein of 694 aas and 9 TMSs.

Eukaryota
Metazoa
UP of Solenopsis invicta (Red imported fire ant) (Solenopsis wagneri)
*2.A.112.4.3









Uncharacterized protein of 615 aas and 9 TMSs

Eukaryota
Metazoa
UP of Aedes aegypti (Yellowfever mosquito) (Culex aegypti)