The major function of titin in muscle contraction is to:
Massive protein titin, encoded by TTN gene 363 exons, 38,138 residues in canonical cardiac isoform N2B 3.8 megadalton, spans half sarcomere from Z disc to M line, single molecule. N terminal Z disc anchor binds alpha actinin via Z repeats 1 to 7 and telethonin T cap forming antiparallel complex, I band extensible region contains tandem immunoglobulin like domains Ig 80 repeats that unfold at low force providing entropic elasticity, PEVK region rich in proline glutamate valine lysine behaving as worm like chain, and cardiac specific N2B element with spring properties. A band region with FN3 and
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 17: Titin Elasticity and Myosin Binding.
