The giant protein titin: a regulatory node that integrates myocyte signaling pathways

Titin, the largest protein in the human body, is well known as a molecular spring in muscle cells and scaffold protein aiding myofibrillar assembly. However, recent evidence has established another important role for titin: that of a regulatory node integrating, and perhaps coordinating, diverse signaling pathways, particularly in cardiomyocytes. We review key findings within this emerging field, including those related to phosphorylation of the titin springs, and also discuss how titin participates in hypertrophic gene regulation and protein quality control.