( Also ( , ( ( for ( organisms ( that ( ( do not ) ( have ( titin ( as ( their ( main ( structural protein ) ) ) ) ) ) ) ) ) ) ( , ( maybe ( ( their ( specific proteins ) ) ( ( have ( ( ( a region ) ( like ( that ( of titin ) ) ) ) ( which ( is ( rich ( in ( specific ( amino acids ) ) ) ) ) ) ) ) . ) ) ) ) ) ) )
(ROOT (S (ADVP (RB Also)) (, ,) (PP (IN for) (NP (NP (NNS organisms)) (SBAR (WHNP (WDT that)) (S (VP (VBP do) (RB not) (VP (VB have) (VP (VBN titin) (PP (IN as) (NP (PRP$ their) (JJ main) (JJ structural) (NN protein)))))))))) (, ,) (ADVP (RB maybe)) (NP (PRP$ their) (JJ specific) (NNS proteins)) (VP (VBP have) (NP (NP (DT a) (NN region)) (PP (IN like) (NP (NP (DT that)) (PP (IN of) (NP (NN titin))))) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADJP (JJ rich) (PP (IN in) (NP (JJ specific) (JJ amino) (NNS acids))))))))) (. .)))
Also, for organisms that do not have titin as their main structural protein, maybe their specific proteins have a region like that of titin which is rich in specific amino acids.
(ROOT (S (NP (DT The) (ADJP (JJS largest) (VBN known)) (NNS proteins)) (VP (VBP are) (ADJP (JJ titins))) (. .)))