E3 ubiquitin-protein ligase TRIM63; tripartite motif-containing protein 63; muscle-specific RING finger protein 1; MURF-1; MuRF1; RING finger protein 28; striated muscle RING zinc finger protein; Iris RING finger protein (TRIM63, IRF, MURF1, RNF28, SMRZ)
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Function
- E3 ubiquitin ligase
- regulates proteasomal degradation of cardiac troponin I (TNNI3) & probably of other sarcomeric-associated proteins
- may play a role in striated muscle atrophy & muscle hypertrophy by regulating an anti-hypertrophic PKC-mediated signaling pathway
- may regulate the organization of myofibrils through TTN in muscle cells
- protein modification; protein ubiquitination
- interacts with SUMO2, titin/TTN & GMEB1
- interacts with TRIM54 & probably with TRIM55 & TNNI3
- forms a ternary complex with GNB2L1 & PRKCE
- required for the E3 ubiquitin ligase activity (putative)
Structure
- homooligomer & heterooligomer
- the RING-type Zn+2 finger mediates interaction with SUMO2 & localization to the nucleus
- contains 1 B box-type Zn+2 finger
- contains 1 COS domain
- contains 1 RING-type Zn+2 finger
Compartment
- cytoplasm (putative), nucleus
- localizes to the M-lines & Z-lines in skeletal muscle
- colocalizes with TNNI3 in myocytes (putative)
Expression
- muscle specific
- selectively expressed in heart muscle & skeletal muscle
- also expressed in the iris
- expressed throughout all developmental stages
Pathology
- upregulated in striated muscle atrophy
Notes
It is uncertain whether Met-1 or Met-14 is the initiator