S100A1 Protein, Human

S100A1 is a small calcium-binding protein that plays crucial roles in various biological processes, including Ca(2+) homeostasis, chondrocyte biology, and cardiomyocyte regulation. Upon an increase in intracellular Ca(2+) levels, S100A1 binds calcium, triggering conformational changes that facilitate interactions with specific target proteins, subsequently modulating their activity. Particularly, in cardiomyocytes, S100A1 orchestrates a network governing sarcoplasmic reticulum Ca(2+) cycling and mitochondrial function by interacting with key proteins such as ryanodine receptors RYR1 and RYR2, sarcoplasmic reticulum Ca(2+)-ATPase/ATP2A2, and mitochondrial F1-ATPase. This multifaceted protein also contributes to diastolic Ca(2+) dissociation and myofilament mechanics, enhancing relaxation during diastole. S100A1 exists as a dimer of either two alpha chains, two beta chains, or one of each, and it forms heterodimers with S100P. Additionally, it engages in various interactions with proteins like AGER, CAPZA1, FKBP4, RYR1, RYR2, CACYBP, PPP5C, ATP2A2, PLN, ATP5F1A, and ATP5F1B, participating in diverse cellular processes in a calcium-dependent manner.