Recombinant Human STAM-1 Protein, CF

Signal Transducing Adaptor Molecule-1 (STAM-1) is a member the STAM family of adaptor molecules. This ubiquitously expressed protein is 540 amino acids (aa) in length with a predicted molecular weight of 59.18 kDa. Human STAM-1 shares 91% and 92% aa sequence identity with the rat and mouse orthologs, respectively. It contains multiple domains including a VHS domain (aa 16-143) and a Ubiquitin-interacting motif (aa 171-190), both of which bind ubiquitinated proteins, a SH3 domain (aa 210-269) that associates with the zinc metalloprotease STAMBP, and an ITAM domain (aa 370-387), which contains a Hrs-binding site and interacts with Janus kinases (Jaks) (1-6). STAM-1 is involved in downstream signaling stimulated by cytokines and growth factors. It is tyrosine phosphorylated by Jaks in response to a variety of cytokines including IL-2, IL-3, IL-4, IL-7, GM-CSF, EGF, and PDGF, and has been shown to induce DNA synthesis and MYC expression (1,2,5). Additionally, STAM-1 has been shown to regulate CXCR4 signaling and appears to be important for T cell development and survival (7,8). Besides its role in signal transduction, STAM-1 may also be important for the regulation of endocytic membrane trafficking. It associates with Hrs to form the endosomal sorting complex required for transport-0 (ESCRT-0) complex, which binds to ubiquitinated membrane proteins on early endosomes and directs them to the ESCRT-1 complex for lysosomal degradation (6, 9-11). STAM-1 has also been shown to interact with coat protein II complexes and function in trafficking vesicles from the endoplasmic reticulum to the Golgi apparatus (12). This full-length recombinant human protein has no intrinsic deubiquitinase activity but is useful in stimulating the in vitro activity of the JAMM-class deubiquitinase AMSH.