Helix 1-3 is an N-terminal that is composed of three antiparallel helices that are arranged in an up, down, up pattern. Helix 4 is a C-terminal made up of an antiparallel β sheet which is composed of five β strands. On one side of the C-terminal, there is a shorter N-terminal helix and a long C-terminal helix.
This long C-terminal helix makes up helix 5. The final helix, helix 6 differs in the α and β subunits. The β subunit is longer than the α subunit.