MurF1 (<strong>M</strong>uscle-specific <strong>R</strong>ING-<strong>F</strong>inger protein 1) is a RING-finger E3 ligase found in striated muscle (heart and skeletal) and iris tissues. MurF1 shares 62% and 77% sequence homology with MurF2 and MurF3 respectively. The protein contains a RING-finger/B-box/coiled-coil tripartite fold known as TRIM, and it can form homo- and hetero-oligomers vial the coiled-coil dimerization motifs. The N-terminal E3 ligase activity regulates the proteasomal degradation of cardiac troponin and probably other sarcomeric-associated proteins. The exact cellular roles and substrates for MurF1 are not yet known but it interacts with various proteins including titin, isopeptidase3, SUMO-3, UbcH9 and GMEB-1. MurF1 may have a role in muscle adaptation, atrophy and hypertrophy mediated by ubiquitin-proteasome pathways (UPP). Muscle atrophy is associated with many diseases including cancer, diabetes and AIDS.