second type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 1 (PCBP1) and similar proteins
The family includes PCBP1 (also called alpha-CP1, or heterogeneous nuclear ribonucleoprotein E1, or hnRNP E1, or nucleic acid-binding protein SUB2.3) and PCBP2 (also called alpha-CP2, or heterogeneous nuclear ribonucleoprotein E2, or hnRNP E2). They are single-stranded nucleic acid binding proteins that bind preferentially to oligo dC. They act as iron chaperones for ferritin. In case of infection by poliovirus, PCBP1 plays a role in initiation of viral RNA replication in concert with the viral protein 3CD. PCBP2 is a major cellular poly(rC)-binding protein. It also binds poly(rU). PCBP2 negatively regulates cellular antiviral responses mediated by MAVS signaling. It acts as an adapter between MAVS and the E3 ubiquitin ligase ITCH, therefore triggering MAVS ubiquitination and degradation. PCBP2 forms a metabolon with the heme oxygenase 1/cytochrome P450 reductase complex for heme catabolism and iron transfer. Both PCBP1 and PCBP2 contain three K-homology (KH) RNA-binding domains. The model corresponds to the second one.