( ( ( ( ( IgD ( is ( confined ( to ( the ( cell membrane ) ) ) ) ) ) , ) but ) ( IgM ( can ( exist ( in ( ( ( ( ( ( ( two functionally ) and ) ( ( structurally distinct ) forms ) ) , ) ( membrane-bound ( -LRB- ( mIgM -RRB- ) ) ) ) and ) ( secreted ( -LRB- ( sIgM -RRB- ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNP IgD)) (VP (VBZ is) (VP (VBN confined) (PP (TO to) (NP (DT the) (NN cell) (NN membrane)))))) (, ,) (CC but) (S (NP (NNP IgM)) (VP (MD can) (VP (VB exist) (PP (IN in) (NP (NP (CD two) (NN functionally)) (CC and) (NP (ADJP (RB structurally) (JJ distinct)) (NNS forms)) (, ,) (NP (JJ membrane-bound) (-LRB- -LRB-) (NN mIgM) (-RRB- -RRB-)) (CC and) (NP (JJ secreted) (-LRB- -LRB-) (NN sIgM) (-RRB- -RRB-))))))) (. .)))
IgD is confined to the cell membrane, but IgM can exist in two functionally and structurally distinct forms, membrane-bound (mIgM) and secreted (sIgM).
(ROOT (S (NP (CD Two) (NNS membranes)) (VP (VBP form) (NP (NP (DT the) (NN mitochondrion) (NN structure)) (PP (IN of) (NP (DT a) (NN cell))))) (. .)))