Degenerated RING (dRING) finger found in Saccharomyces cerevisiae required for meiotic nuclear division protein 5 (Rmd5p) and similar proteins
Rmd5p, also known as glucose-induced degradation protein 2 (Gid2) or sporulation protein RMD5, is an E3 ubiquitin ligase containing a Lissencephaly type-1-like homology motif (LisH), a C-terminal to LisH motif (CTLH) domain, and a degenerated RING finger that is characterized by lacking the second, fifth, and sixth Zn2+ ion-coordinating residues compared with the classic C3H2C3-/C3HC4-type RING fingers. It forms the heterodimeric E3 ligase unit of the glucose induced degradation deficient (GID) complex with Gid9 (also known as Fyv10), which has a degenerated RING finger as well. The GID complex triggers polyubiquitylation and subsequent proteasomal degradation of the gluconeogenic enzymes fructose-1, 6-bisphosphate by fructose-1, 6-bisphosphatase (FBPase), phosphoenolpyruvate carboxykinase (PEPCK), and cytoplasmic malate dehydrogenase (c-MDH). Moreover, Rmd5p can form the GID complex with the other six Gid proteins, including Gid1/Vid30, Gid4/Vid24, Gid5/Vid28, Gid7, Gid8, and Gid9/Fyv10. The GID complex in which the seven Gid proteins reside functions as a novel ubiquitin ligase (E3) involved in the regulation of carbohydrate metabolism.
Comment:The degenerated RING finger is characterized by lacking the second, fifth, and sixth Zn2+ ion-coordinating residues compared with the classic C3H2C3-/C3HC4-type RING fingers, similar to SP-RING fingers.
Comment:based on the structures of human Sumo ligases Pias2 and Pias3 with bound Zn2+ ion through their SP-RING fingers
Comment:The SP-RING finger is a variant of RING finger; it binds a single Zn ion and lacks the second, fifth, and sixth zinc-binding residues of the consensus C3H2C3-/C3HC4-type RING fingers.
Jiyao W et al.(2023). "The conserved domain database in 2023.",