Tripartite Motif Containing Protein 63 (TRIM63)

TRIM63 is localized to the Z-line and M-line lattices of myofibrils, where titin's N-terminal and C-terminal regions respectively bind to the sarcomere. Another member of this protein family binds to microtubules. RNF28 shares 62% and 77% sequence homology with RNF29 and RNF30, respectively. All 3 proteins share a conserved N-terminal RING domain and zinc-binding B-box motif as well as 2 coiled-coil dimerization motif boxes in their central regions. In vitro, they form dimers/heterodimers by shared coiled-coil motifs. Dot-blot analysis demonstrated muscle-specific expression of RNF28 and RNF30, but low-level expression of RNF29 in liver in addition to expression in striated muscle. RNF28 is expressed in all striated muscle tissues throughout development.