Figure 18.

Diagram of the Z-band region of a cardiac muscle illustrating the relationships of the thin actin filaments, titin molecules, telethonin, and α-actinin. Through defined binding domains, α-actinin cross links actin filaments and binds the thin filament protein, nebulette, as well as titin filaments. Our hypothesis is that the Z-band protein, ArgBP2, links the myofibril to the cardiomyocyte membrane (T-tubule and the SR = sarcoplasmic reticulum) and to bind molecules of the signal transduction machinery that respond to extracellular stimuli. Drawing is not to scale.