The propeptide of pulmonary surfactant C has an N-terminal alpha-helical segment whose suggested function was stabilization of the protein structure, since the mature peptide can irreversibly transform from its native alpha-helical structure to beta-sheet aggregates and form amyloid fibrils.
A segment in the propeptide of pulmonary surfactant C has an N-terminal alpha-helix that is thought to play a role in maintaining the protein's three-dimensional shape, but it can change into beta-sheets and form amyloid fibers when matured.