( ( The channels ) ( ( enable ( ( potassium ions ) ( to ( cross ( the ( cell membrane ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS channels)) (VP (VBP enable) (S (NP (NN potassium) (NNS ions)) (VP (TO to) (VP (VB cross) (NP (DT the) (NN cell) (NN membrane)))))) (. .)))
The channels enable potassium ions to cross the cell membrane.
(ROOT (NP (NP (NP (NNP Ion) (NNP channels) (NNP facilitate)) (PRN (-LRB- -LRB-) (PRP s) (-RRB- -RRB-))) (NP (NP (DT the) (NN diffusion)) (PP (IN of) (NP (NP (NNS ions)) (PP (IN across) (NP (DT a) (NN membrane)))))) (. .)))