sentence: The giant elastic protein titin ( connectin ) spans the distance from the Z-line to the M-line in the striated muscle sarcomere and serves as a molecular ruler for self-assembly of sarcomere proteins during myofibrillogenesis , as well as a passive force generator ( e.g ., Whiting et al ., 1989 ; Trinick , 1994 ; Gregorio et al ., 1999 ; Granzier and Labeit , 2004 ) .