( Titin ( ( ( ( is ( the ( ( largest known ) ( single-subunit protein ) ) ) ) , ) ( with ( ( a ( molecular weight ) ) ( of ( about ( three million ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Titin)) (VP (VBZ is) (NP (DT the) (ADJP (JJS largest) (VBN known)) (JJ single-subunit) (NN protein)) (, ,) (PP (IN with) (NP (NP (DT a) (JJ molecular) (NN weight)) (PP (IN of) (NP (QP (RB about) (CD three) (CD million))))))) (. .)))
Titin is the largest known single-subunit protein, with a molecular weight of about three million.
(ROOT (S (NP (DT The) (ADJP (JJS largest) (VBN known)) (NNS proteins)) (VP (VBP are) (ADJP (JJ titins))) (. .)))