There are 11 nucleotide differences between Dmau\mariner\Tpch and a functional mariner transposase; 3 changes upstream of the open reading frame, four missense and one silent substitution within the open reading frame, and 3 changes downstream of the open reading frame.
Dmau\mariner\Tpch encodes a non-functional transposase which is inserted into Dmau\wpch.