Regulates signaling cascades probably through protein ubiquitination and/or sequestration. Functions in insulin signaling and glucose homeostasis through IRS1 ubiquitination and subsequent proteasomal degradation. Inhibits also prolactin, growth hormone and leptin signaling by preventing STAT3 and STAT5 activation, sequestering them in the cytoplasm and reducing their binding to DNA. May be a substrate recognition component of a SCF-like E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (By similarity). Protein modification; protein ubiquitination. Interacts with phosphorylated IRS4 and PIK3R1 (By similarity). Interacts, via the third proline-rich region, with the second SH3 domain of the adapter protein NCK1. Also interacts with GRB2, INSR, IRS1, PLCG1, SORBS3/vinexin, and phosphorylated STAT3 and STAT5. Interacts with SEPT6. Mostly cytoplasmic, but shuttles between the cytoplasm and the nucleus. Rapidly relocalizes to the nucleus after UV irradiation. Cytoplasmic location depends upon SEPT7 presence. Expressed in brain and leukocytes. Also in fetal lung fibroblasts and fetal brain. By IL6/interleukin-6, prolactin and growth hormone. The SOCS box domain mediates the interaction with the Elongin BC complex, an adapter module in different E3 ubiquitin ligase complexes (By similarity). It is required for IRS1 ubiquitination and subsequent proteasomal degradation. Contaminating sequence. The N-terminus may be contaminated with vector sequence. Extended C-terminus.