Lck is a member of the Src family of cytoplasmic protein-tyrosine kinases (PTKs). It is normally expressed in lymphoid cells, namely T and NK cells. Repression of Lck catalytic activity occurs via phosphorylation at tyrosine 505 (Y505). Phosphorylation of Y505 is mediated by the Csk family of PTKs, and its dephosphorylation is mediated by the protein tyrosine phosphatase CD45. When Lck is phosphorylated at this site, it assumes a folded tertiary structure that is enzymatically inactive. When CD45 dephosphorylates it at Y505, Lck is able to autophosphorylate its Y394, which leads to conformational changes in the catalytic domain that induce kinase activity. Antibody clone 4/LCK-Y505 recognized the protein sequence containing phosphorylated Y505 on Lck.
Anti-pLck [T505] (4/LCK-Y505)-162Dy—50 Tests