SPRY domain in the suppressor of cytokine signaling 1, 2, 4 families (SOCS1, SOCS2, SOCS4)
The SPRY domain-containing SOCS box protein family (SPSB1-4, also known as SSB-1 to -4) is composed of a central SPRY protein interaction domain and a C-terminal SOCS box. All four SPSB proteins interact with c-Met, the hepatocyte growth factor receptor, but only SPSB1, SPSB2, and SPSB4 interact with prostate apoptosis response protein 4 (Par-4). They are negative regulators that recruit the ECS E3 ubiquitin ligase complex to polyubiquitinate inducible nitric-oxide synthase (iNOS), resulting in its proteasomal degradation, thus contributing to protection against the cytotoxic effect of iNOS in activated macrophages. It has been shown that SPSB1 and SPSB4 induce the degradation of iNOS more strongly than SPSB2. The Drosophila melanogaster SPSB1 homolog, GUSTAVUS, interacts with the DEAD box RNA helicase Vasa. Suppressor of cytokine signaling (SOCS) proteins negatively regulate signaling from JAK-associated cytokine receptor complexes, and play key roles in the regulation of immune homeostasis.
Jiyao W et al.(2023). "The conserved domain database in 2023.",