Figure 1.

In healthy cardiomyocytes (A), t-tubule cBIN1-microdomains regulate intracellular calcium handling through: (1) facilitating forward delivery of L-type calcium channels (LTCCs) via plus-end tracking protein (+TIP) tipped microtubules (MT); (2) clustering LTCCs that are already delivered to t-tubule surface; (3) recruiting ryanodine receptors (RyRs) at the junctional sarcoplasmic reticulum (jSR) for effective dyad formation; (4) organizing a subpopulation of SERCA2a near the jSR; and (5) creating an extracellular slow ion diffusion zone. All of these functions are disrupted in failing cardiomyocytes (B).