Hypothetical structure of a KLH2 pentadecamer. This model was obtained by fusing two extracted decamers, at a rotation angle of 36°, with the 30-Å structure of the KLH2 tridecamer. Orientation of the five decamers is indicated by their collar complexes (golden); note that the right-handed helical structure of the cylinder wall is steadily continued, as shown here in each decamer for a subunit dimer (purple). The pitch of the surface helical feature, with respect to the longitudinal axis, is 45° (see also [2, 15]). The pitch height (frequency of twist) of the right-handed helix is 4.5 subunit dimers, meaning that in the pentadecamer the helix completes 360°.