( ( Gprotein ( , ( phosphorylation ( , ( ion ( channels ( , ( second messenger ) ) ) ) ) ) ) ) ( pathways . ) )
(ROOT (S (NP (NN Gprotein) (, ,) (NN phosphorylation) (, ,) (NN ion) (NNS channels) (, ,) (JJ second) (NN messenger)) (VP (VBZ pathways)) (. .)))
Gprotein, phosphorylation, ion channels, second messenger pathways.
(ROOT (S (NP (NNP Calcium) (NNP ion)) (VP (VBZ is) (NP (NP (DT an) (NN example)) (PP (IN of) (NP (DT a) (JJ second) (NN messenger))))) (. .)))
Calcium ion is an example of a second messenger.