Signal-regulatoryprotein beta-1 (SIRPB1, CD172b) is a member of the signal-regulatory-protein (SIRP) family, and also belongs to the immunoglobulin superfamily. SIRP family members are receptor-type transmembrane glycoproteins known to be involved in the negative regulation of receptor tyrosine kinase-coupled signaling processes. This protein was found to interact with TYROBP DAP12, a protein bearing immunoreceptor tyrosine-based activation motifs. This protein was also reported to participate in the recruitment of tyrosine kinase SYK.
CD47 (Cluster of Differentiation 47) also known as integrin associated protein (IAP) is a transmembrane protein that in humans is encoded by the CD47 gene. CD47 belongs to the immunoglobulin superfamily and partners with membrane integrins and also binds the ligands thrombospondin-1 (TSP-1) and signal-regulatoryprotein alpha (SIRPα).CD-47 acts as a don't eat me signal to macrophages of the immune system which has made it a potential therapeutic target in some cancers.
Hydroxyacid oxidase 1, also known as Glycolate oxidase, HAO1, and GOX1, is a member of the FMN-dependent alpha-hydroxy acid dehydrogenase family. HAO1 GOX1 has 2-hydroxyacid oxidase activity. It is most active on the 2-carbon substrate glycolate, but is also active on 2-hydroxy fatty acids, with high activity towards 2-hydroxy palmitate and 2-hydroxy octanoate. HAO1 GOX1 is a liver-specific peroxisomal enzyme that oxidizes glycolate to glyoxylate with the concomitant production of H2O2. In Hao1 messenger RNA (mRNA), an iron-responsive element (IRE) homologous to the sequence recognized by iron regulatoryproteins (IRP), key regulators of iron homeostasis, is present. Mammalian HAO1 GOX1 is a peroxisomal protein and that the C-terminal sequence SKI acts as the targeting signal. Down-regulation of HAO1 GOX1 expression during oxidative stress may provide a mechanism to prevent excessive H2O2 formation in liver peroxisomes and may represent the prototype of a poorly recognized but potentially relevant response to an oxidative injury involving down-regulation of ROS-producing enzymes.