( ( He ( discovered ( ( the cell ) ( membrane ( protein molecules ) ) ) ) ) ( , ( ( called ( ( ( ion channels ) , ) ( that ( generate ( ( electrical signals ) ( in ( nerve ( and ( muscle cells ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (SINV (S (NP (PRP He)) (VP (VBD discovered) (SBAR (S (NP (DT the) (NN cell)) (VP (VBZ membrane) (NP (NN protein) (NNS molecules))))))) (, ,) (VP (VBD called)) (NP (NP (NN ion) (NNS channels)) (, ,) (SBAR (WHNP (WDT that)) (S (VP (VBP generate) (NP (NP (JJ electrical) (NNS signals)) (PP (IN in) (NP (NN nerve) (CC and) (NN muscle) (NNS cells)))))))) (. .)))
He discovered the cell membrane protein molecules, called ion channels, that generate electrical signals in nerve and muscle cells.
(ROOT (S (NP (NP (DT An) (JJ electrical) (NN signal)) (PP (IN along) (NP (DT a) (NN nerve) (NN cell)))) (VP (VBZ triggers) (NP (NP (DT the) (NN secretion)) (PP (IN of) (NP (NN neurotransmitter) (NNS molecules))))) (. .)))