PLN

PLN (Phospholamban): Phospholamban is a regulatory protein primarily found in cardiac muscle cells, where it plays a crucial role in the regulation of cardiac contractility and relaxation. This small transmembrane protein modulates the activity of the sarcoplasmic reticulum calcium ATPase (SERCA), which is responsible for pumping calcium ions back into the sarcoplasmic reticulum during cardiac relaxation. By inhibiting SERCA at baseline conditions, PLN helps maintain calcium homeostasis and prevents excessive calcium uptake during diastole. However, upon stimulation, PLN is phosphorylated, relieving its inhibitory effect on SERCA and enhancing calcium reuptake, thereby promoting cardiac muscle relaxation and ensuring efficient cardiac function. Dysregulation or mutations in PLN can lead to impaired calcium handling, contributing to cardiac arrhythmias and heart failure. Understanding the intricate role of PLN in cardiac physiology provides insights into potential therapeutic strategies targeting calcium handling abnormalities in cardiovascular diseases.