SH2D3A is a 576 amino acid protein that is thought to play a role in JNK activation. SH2D3A interacts with p130 Cas and is found at low levels in fetal kidney, fetal lung, placenta, adult pancreas, kidney and lung. Subject to post-translational phosphorylation on multiple tyrosine residues, SH2D3A contains one Src homology 2 (SH2) domain. SH2 domains bind to tyrosine-phosphorylated regions of target proteins, frequently linking activated growth factors to putative signal transduction proteins. The gene encoding SH2D3A 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 families and Fc receptors (FcRs).