Keyhole limpet hemocyanin
![9Å cryoEM reconstruction of Keyhole limpet hemocyanin (KLH). EMDB entry EMD-1569. [1]](/uploads/202501/22/EMDB1569_KLH0046.png)
Keyhole limpet hemocyanin (KLH) is a large, multisubunit, oxygen-carrying, metalloprotein that is found in the hemolymph of the giant keyhole limpet, Megathura crenulata, a species of keyhole limpet that lives off the coast of California, from Monterey Bay to Isla Asuncion off Baja California.