SAM (sterile alpha motif) domain of DGK-delta subfamily proteins is a protein-protein interaction domain. Proteins of this subfamily are multidomain diacylglycerol kinases with a SAM domain located at the C-terminus. DGK-delta proteins participate in signal transduction. They regulate the level of second messengers such as diacylglycerol and phosphatidic acid. In particular DGK-delta is involved in the regulation of clathrin-dependent endocytosis. The SAM domain of DGK-delta proteins can form high molecular weight homooligomers through head-to-tail interactions as well as heterooligomers with the SAM domain of DGK-eta proteins. The oligomerization plays a role in the regulation of the DGK-delta intracellular localization: it inhibits the translocation of the protein to the plasma membrane from the cytoplasm. The SAM domain also can bind Zn at multiple (not conserved) sites driving the formation of highly ordered large sheets of polymers, thus suggesting that Zn may play important role in the function of DCK-delta.
Structure:3BQ7; human SAM/SAM complex of DGK delta1 formed by the end-helix (EH) surface of 3BQ7_A and the mid-loop (ML) surface of 3BQ7_B, contacts at 4A.
Comment:SAM domains of DGK delta1 proteins interact to each other in head-to-tail manner (ML surface interacts with EH surface).
Jiyao W et al.(2023). "The conserved domain database in 2023.",