InterPro domain: IPR035773

This SPRY domain is found at the N terminus of RING finger protein 123 (also known as E3 ubiquitin-protein ligase RNF123, KPC1). The ring finger domain motif is present in a variety of functionally distinct proteins and known to be involved in protein-protein and protein-DNA interactions. RNF123 displays E3 ubiquitin ligase activity toward the cyclin-dependent kinase inhibitor p27 (Kip1) [ 1 ] and p105 and inhibits tumor growth via regulation of p50-dependent tumor suppressor genes [ 2 ].

Proteins containing this domain also include AtKPC1 from Arabidopsis. AtKPC1 is an E3 ubiquitin-protein ligase that promotes the ubiquitination and proteasomal degradation of KRP1 and KRP2 [ 3 , 4 ].

1. Cytoplasmic ubiquitin ligase KPC regulates proteolysis of p27(Kip1) at G1 phase. Nat. Cell Biol. 6, 1229-35
2. KPC1-mediated ubiquitination and proteasomal processing of NF-κB1 p105 to p50 restricts tumor growth. Cell 161, 333-47
3. Degradation of the cyclin-dependent kinase inhibitor KRP1 is regulated by two different ubiquitin E3 ligases. Plant J. 53, 705-16
4. RKP, a RING finger E3 ligase induced by BSCTV C4 protein, affects geminivirus infection by regulation of the plant cell cycle. Plant J. 57, 905-17