Cyclooxygenases (COX-1, COX-2 ...) seems to be very popular in the community, but I cannot find any crystal structure of homo sapiens cyclooxygenases, neither in RCSB PDB or anywhere else. What exist are all of other organisms, such as ovis aries. No one succeeded in analyzing the structures of homo sapiens COXs? Is this the case or I did not look for it correctly?