▁release ▁of ▁a ▁sol ub le ▁e ct od om ain ▁from ▁memb rane - bound ▁pro - prote ins ▁( such ▁as ▁pro - T NF - α ), ▁and ▁is ▁of ▁known ▁phys i ological ▁importance . ▁AD AM 1 7 ▁was ▁the ▁first ▁' sh ed d ase ' ▁to ▁be ▁identified , ▁and ▁is ▁also ▁understood ▁to ▁play ▁a ▁role ▁in ▁the ▁release ▁of ▁a ▁diverse ▁variety ▁of ▁memb rane - anch ored ▁cy tok ines , ▁cell ▁ad hes ion ▁mole cules , ▁re cept ors , ▁lig ands , ▁and ▁en zym es . ▁ ▁Cl oning ▁of ▁the ▁T NF - α ▁gene ▁revealed ▁it ▁to ▁encode ▁a ▁ 2 6   k Da ▁type ▁II ▁transm emb rane ▁pro - pol ype pt ide ▁that ▁becomes ▁inserted ▁into ▁the ▁cell ▁memb rane ▁during ▁its ▁m atur ation . ▁At ▁the ▁cell ▁surface , ▁pro - T NF - α ▁is ▁bi olog ically ▁active , ▁and ▁is ▁able ▁to ▁indu ce ▁imm une ▁responses ▁via ▁ju xt ac r ine ▁inter cell ular ▁signal ing . ▁However , ▁pro - T NF - α ▁can ▁under go ▁a ▁prote ol yt ic ▁cle av age ▁at ▁its ▁A la 7 6 - Val 7 7 ▁am ide ▁bond , ▁which ▁releases ▁a ▁sol ub le ▁ 1 7 k Da ▁ext rac ell ular ▁domain ▁( ect od om ain ) ▁from ▁the ▁pro - T NF - α ▁mole c ule . ▁This ▁sol