Table 2.

Summary of the domains presented within each surfactant protein

Type	Structure	Function
SP-A/SP-D	N-terminal domain	Stabilization of the oligomeric structure through cysteine-rich region (disulfide bond)
	Collagen-like domain	Maintenance of molecule shape
	Neck domain	Nucleation point for refolding
	Carbohydrate recognition domain	Binding to lipopolysaccharide or carbohydrates at the surface of microorganisms
SP-B/SP-C	N-terminal domain	Dimerization through Cys residues (SP-B) Formation of an amphipathic β-hairpin (SP-C)
	C-terminal domain	Additional saposin-like domains in proSP-B (SP-B) Stabilization of the proper folding of extremely hydrophobic transmembrane (SP-C)