Tripartite motif-containing protein 5 (TRIM5)

Tripartite motif-containing protein 5 (TRIM5), especially its α (alpha) isoform, is an **innate immune restriction factor** found in mammalian cytoplasm[1][5]. It consists of a tripartite motif (RING E3 ubiquitin ligase domain, B-box domain, and coiled-coil domain) and a C-terminal PRYSPRY (or SPRY or B30.2) domain[2][5]. TRIM5α recognizes and binds to the capsids of incoming retroviruses, including HIV-1, via the SPRY domain, then self-assembles into a hexagonal lattice around the capsid[1][2][3]. This restricts infection by interfering with capsid uncoating, blocking reverse transcription and nuclear import of viral genome, and targeting capsid proteins for proteasome-mediated degradation[1][5]. As an E3 ubiquitin ligase, TRIM5 modulates downstream signaling pathways, including NF-κB and AP-1 via TAK1 kinase activation, contributing to the innate immune response[5]. TRIM5α's restriction specificity is determined by its variable C-terminal domain, which evolutionarily diversifies in primates and other mammals to protect against differing retroviral threats. No approved drugs directly target TRIM5[1][5].

Other names

TRIM5αRNF88RING finger protein 88TRIM5alphaRING-type E3 ubiquitin transferase TRIM5tripartite motif protein TRIM5tripartite motif-containing protein 5 alpha

Not applicable for classic drugs; no known drugs that specifically target TRIM5 are currently approved. Its mechanism of action is as a restriction factor: recognizes retroviral capsid, assembles into a hexagonal lattice encaging the capsid, mediates proteasome-dependent degradation, and triggers immune signaling[1][5].