Triadin2

Triadin2 is an isoform of triadin, a family of integral membrane proteins associated with the sarcoplasmic reticulum (SR) in skeletal and cardiac muscle. It is produced from the TRDN gene through alternative RNA splicing and represents one of several triadin variants that contribute to the organization of the calcium release unit in muscle cells.

Triadin proteins typically embed in the SR membrane with a transmembrane helix and oriented termini, enabling interactions on both the cytosolic and luminal sides of the SR. Triadin2, like other isoforms, is thought to differ from its relatives in its N-terminal region, which can influence subcellular localization, stability, and binding properties. The exact expression pattern of Triadin2 can vary by species and tissue, and reports indicate its presence in cardiac and skeletal muscle samples, though precise distribution data are less well defined compared with other triadin isoforms.

Functionally, triadins participate in calcium handling by linking the ryanodine receptor (RyR) to calsequestrin and other SR proteins, thereby modulating RyR channel activity in response to luminal calcium levels. Triadin2 is presumed to contribute to this regulatory network, helping to anchor and stabilize the calcium release complex and influence excitation-contraction coupling efficiency in muscle cells.

Genetically, variants in the TRDN gene, which encodes triadin proteins including Triadin2, have been associated with disruptions in calcium release and conditions such as catecholaminergic polymorphic ventricular tachycardia and related myopathies. However, detailed functional characterization specific to Triadin2 remains limited, and most reported phenotypes reflect the broader impact of TRDN-derived triadin dysfunction on SR calcium release.