PRY/SPRY domain in tripartite motif-containing (TRIM) proteins, including TRIM14-like, TRIM16-like, TRIM25-like, TRIM47-like, TRIM65 and RNF135, and stonustoxin
This domain, consisting of the distinct N-terminal PRY subdomain followed by the SPRY subdomain, is found at the C-terminus of several Class I TRIM proteins, including TRIM14, TRIM16 and TRIM25, TRIM47 as well as RING finger protein RNF135 and stonustoxin, a secreted poisonous protein of the stonefish Synanceja horrida. TRIM16 (also known as estrogen-responsive B box protein or EBBP) has E3 ubiquitin ligase activity. It is a regulator of keratinocyte differentiation and a tumor suppressor in retinoid-sensitive neuroblastoma. TRIM25 (also called Efp) ubiquitinates the N terminus of the viral RNA receptor retinoic acid-inducible gene-I (RIG-I) in response to viral infection, leading to activation of the RIG-I signaling pathway, thus resulting in type I interferon production to limit viral replication. It has been shown that the influenza A virus targets TRIM25 and disables its antiviral function. TRIM47, also known as GOA (Gene overexpressed in astrocytoma protein) or RNF100 (RING finger protein 100), is highly expressed in kidney tubular cells, but low expressed in most tissue. It is overexpressed in astrocytoma tumor cells and plays an important role in the process of dedifferentiation that is associated with astrocytoma tumorigenesis. RNF135 ubiquitinates RIG-I (retinoic acid-inducible gene-I) to promote interferon-beta induction during the early phase of viral infection. Stonustoxin (STNX) is a hypotensive and lethal protein factor that also possesses other biological activities such as species-specific hemolysis (due to its ability to form pores in the cell membrane) and platelet aggregation, edema-induction, and endothelium-dependent vasorelaxation (mediated by the nitric oxide pathway and activation of potassium channels). The PRY-SPRY domain in these TRIM families is suggested to serve as the target binding site.