The adaptor proteins downstream of kinase 1 (DOK1) to DOK3 are mainly found in immune cells, and they are closely related, with some functional redundancy, although each DOK protein has distinct properties and functions. DOK1 to DOK3 inhibit LPS responses. DOK proteins have an N-terminal pleckstrin homology (PH) domain, a phosphotyrosine-binding (PTB) domain, and four tyrosine-containing motifs that can bind to Src homology 2 (SH2) domains when phosphorylated. DOK3 was also shown to have an inhibitory role as it restricts Ca2+ and JNK activation in B cell receptor signaling. The MW of this protein is 53 kDa, and this antibody specially recognises the 53 kDa protein.