osis ▁is ▁initi ated ▁through ▁infl ux ▁of ▁Ca 2 + , ▁and ▁l am ell ar ▁memb rane ▁f uses ▁with ▁pl asma ▁memb rane ▁to ▁release ▁sur fact ant ▁ph osph ol ip id ▁contents ▁into ▁the ▁surface ▁of ▁the ▁cell . ▁SP - B ▁and ▁SP - C ▁are ▁responsible ▁to ▁carry ▁out ▁ad s or ption ▁of ▁the ▁li pid ▁mon ol ayer ▁at ▁the ▁liquid - air ▁inter phase ▁to ▁prevent ▁post ▁exp iration ▁a te lect asis . ▁U sed ▁sur fact ant ▁ph osph ol ip id ▁materials ▁are ▁taken ▁up ▁into ▁ep ith el ial ▁type ▁II ▁cells ▁by ▁pul mon ary ▁macro ph ages . ▁ ▁Another ▁important ▁protein ▁that ▁cont ributes ▁to ▁outcome ▁of ▁sur fact ant ▁met abol ism ▁d ys function ▁is ▁ABC A 3 , ▁a ▁transm emb rane ▁ph osph ol ip id ▁trans porter ▁in ▁l am ell ar ▁body . ▁ABC A 3 ▁has ▁two ▁ATP ▁binding ▁sites ▁in ▁the ▁cy top las mic ▁domain ▁to ▁power ▁ph osph ol ip id ▁transport ation ▁through ▁ATP ▁hydro ly s is . ▁ABC A 3 ▁is ▁synth es ized ▁in ▁end op las mic ▁ret icul um ▁and ▁transport ed ▁through ▁Gol gi ▁appar atus ▁to ▁the ▁memb rane ▁of ▁l am ell ar ▁body . ▁Once ▁inserted ▁into ▁the ▁memb rane , ▁ABC A 3 ▁can ▁help ▁deliver ▁sur fact ant ▁lip ids ▁into ▁the ▁l umen ▁of ▁l am ell ar ▁body , ▁and ▁create ▁tight