2.A.1.49.2
The spinster homologue, Spin1 or Spns1 (SLC63A1) of 528 aas and 12 TMSs. It interacts with Bc1-2/Bc1-XL to induce a caspase-independent autophagic cell death (Yanagisawa et al., 2003). It is a spingosine-1-phosphate (S1P) (or sphingolipid) exporter (Nijnik et al. 2012). S1P is important for lymphocyte trafficking, immune responses, vascular and embryonic development, cancer, bone homeostasis (Zhu et al. 2018). S1P is produced intracellularly and then secreted into the circulation to engage in the above physiological or pathological processes by regulating the proliferation, differentiation and survival of target cells. SPNS2 acts as a mediator of intracellular S1P release. The SPNS1-dependent lysosomal lipid transport pathway enables cell survival under choline limitation (Scharenberg et al. 2023). The orphan lysosomal transmembrane protein SPNS1 is critical for cell survival under choline limitation. SPNS1 loss leads to intralysosomal accumulation of lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE). SPNS1 is a proton gradient-dependent transporter of LPC species from the lysosome for their re-esterification into phosphatidylcholine in the cytosol (Scharenberg et al. 2023).