InterPro domain: IPR005178

This entry includes Organic solute transporter subunit alpha (OSTalpha, also known as SLC51A) and Transmembrane protein 184 (TMEM184).

Ost-alpha protein is a 7-transmembrane (TM) domain containing protein that forms a transporter complex with Ost-beta protein, which is a single-TM domain polypeptide. This heterodimerisation is required for the delivery of the complex to the plasma membrane. The OSTalpha-OSTbeta complex serves as a multispecific transporter that may participate in cellular uptake of bile acids, some endogenous and exogenous steroids, and eicosanoids. It functions via a facilitated diffusion mechanism. Interestingly, this transporter also transports dehydroepiandrosterone sulfate (DHEAS) and pregnenolone sulfate (PREGS), which are major excitatory neurosteroids. This suggests a possible function for OSTalpha-OSTbeta complex in the brain [ 1 ]. In plants this complex may transport brassinosteroid-like compounds and act as regulators of cell death [ 2 ].

Human TMEM184C is a possible tumour suppressor which may play a role in cell growth [ 3 ]. This entry also includes Arabidopsis protein LAZ1, which is required for programmed cell death (PCD) associated with hypersensitive response (HR) [ 4 ].

1. The heteromeric organic solute transporter, OSTα-OSTβ/SLC51: a transporter for steroid-derived molecules. Mol. Aspects Med. 34, 683-92
2. Lazarus1, a DUF300 protein, contributes to programmed cell death associated with Arabidopsis acd11 and the hypersensitive response. PLoS ONE 5, e12586
3. Down-regulation of an inhibitor of cell growth, transmembrane protein 34 (TMEM34), in anaplastic thyroid cancer. J. Cancer Res. Clin. Oncol. 133, 213-8