 The first four domains found in Apolipoprotein H resemble each other, however the fifth one appears to be different.This protein domain is composed of four well-defined anti-parallel beta-strands and two short alpha-helices, as well as a long highly flexible loop.Additionally, the fifth protein domain appears to resemble the other four in Apolipoprotein with the exception of three internal disulfide bonds and an extra C-terminal loop.