SSBP4 (single stranded DNA binding protein 4) is a 385 amino acid nuclear protein that contains one LisH domain and multiple phosphorylated amino acid residues. The gene encoding SSBP4 maps to human chromosome 19, which consists of over 63 million bases, houses approximately 1,400 genes and is recognized for having the greatest gene density of the human chromosomes. It is the genetic home for a number of immunoglobulin (Ig) superfamily members, including the killer cell and leukocyte Ig-like receptors, a number of ICAMs, the CEACAM and PSG family and Fc receptors (FcRs).