DOK proteins are enzymatically inert adaptor or scaffolding proteins. They provide a docking platform for the assembly of multimolecular signaling complexes. DOK3 is a negative regulator of JNK signaling in B-cells through interaction with INPP5D/SHIP1. May modulate ABL1 function. On tyrosine phosphorylation, interacts with CSK and INPP5D/SHIP1 via their SH2 domains. Both Tyr-325 and Tyr-343 are required for interaction with INPP5D. Only Tyr-325 is required for interaction with CSK. Binds ABL1 through the PTB domain and in a kinase-dependent manner. Does not interact with RasGAP. A number of isoforms are produced. Predominantly expressed in bone marrow, spleen and lung. Low levels in heart, brain, liver, muscle, thymus, kidney and testis. Highly expressed in B-cells and macrophages. PTB domain mediates receptor interaction. Constitutively tyrosine-phosphorylated. On IL2 stimulation, phosphorylated on C-terminal tyrosine residues possibly by Src kinases. Can also be phosphorylated by ABL1 kinase. Overexpression of DOK3 inhibits the transforming activity of v-ABL, the ABL oncogene. Major, and shortest isoform. Belongs to the DOK family. Type A subfamily.