os om es ▁ 2 ▁and ▁ 8 ▁respectively . ▁Thus , ▁mut ations ▁on ▁these ▁gen es ▁produce ▁incomplete ▁or ▁non function ing ▁SP - B ▁and ▁SP - C ▁prote ins ▁and ▁lead ▁to ▁lung ▁dise ases . ▁ ▁Both ▁SP - B ▁and ▁SP - C ▁are ▁synth es ized ▁in ▁ep ith el ial ▁type ▁II ▁cells ▁as ▁large ▁prec ursor ▁prote ins ▁( pro SP - B ▁and ▁pro SP - C ) ▁and ▁subsequently ▁cle aved ▁by ▁prote ol yt ic ▁en zym es ▁at ▁both ▁am ino ▁and ▁car box yl ▁term ini ▁to ▁produce ▁functional ▁m ature ▁prote ins . ▁pro SP - B ▁and ▁pro SP - C ▁are ▁first ▁made ▁in ▁the ▁end op las mic ▁ret icul um ▁of ▁ep ith el ial ▁type ▁II ▁cell , ▁they ▁are ▁then ▁trans located ▁through ▁Gol gi ▁appar atus ▁to ▁mult ives icular ▁bodies ▁for ▁delivery ▁to ▁l am ell ar ▁bodies . ▁During ▁this ▁transition , ▁prote ol yt ic ▁processing ▁begins ▁to ▁cle ave ▁prec ursor ▁prote ins . ▁Once ▁mult ives cular ▁body ▁reaches ▁the ▁memb rane ▁of ▁l am ell ar ▁body , ▁both ▁memb ran es ▁f use ▁together ▁so ▁that ▁processed ▁prote ins ▁can ▁be ▁transport ed ▁into ▁l am ell ar ▁body , ▁where ▁last ▁steps ▁of ▁m atur ation ▁for ▁both ▁SP - B ▁and ▁SP - C ▁occur . ▁When ▁l am ell ar ▁body ▁is ▁ready ▁to ▁be ▁secret ed , ▁ex oc yt