InterPro domain: IPR026000

This entry represents a domain found in Apc5 (anaphase-promoting complex subunit 5).

Apc5 is a subunit of the anaphase-promoting complex/cyclosome (APC/C) which is a multisubunit ubiquitin ligase that mediates the proteolysis of cell cycle proteins in mitosis and G1. Tetratricopeptide repeat protein 19 is a mitochondrial protein required for formation of the mitochondrial complex III [ 1 ].

Apc5, although it does not harbour a classical RNA binding domain, Apc5 binds the poly(A) binding protein (PABP), which directly binds the internal ribosome entry site (IRES) of growth factor 2 mRNA. PABP was found to enhance IRES-mediated translation, whereas Apc5 over-expression counteracted this effect. In addition to its association with the APC/C complex, Apc5 binds much heavier complexes and co-sediments with the ribosomal fraction [ 2 , 3 ]. The N terminus of Afi1 serves to stabilise the union between Apc4 and Apc5, both of which lie towards the bottom-front of the APC [ 4 ]. This region of the Apc5 member proteins carries a TPR-like motif.

1. Mutations in TTC19 cause mitochondrial complex III deficiency and neurological impairment in humans and flies. Nat. Genet. 43, 259-63
2. The Apc5 subunit of the anaphase-promoting complex/cyclosome interacts with poly(A) binding protein and represses internal ribosome entry site-mediated translation. Mol. Cell. Biol. 24, 3577-87
3. The anaphase promoting complex/cyclosome: a machine designed to destroy. Nat. Rev. Mol. Cell Biol. 7, 644-56
4. The transcription factor Atf1 binds and activates the APC/C ubiquitin ligase in fission yeast. J. Biol. Chem. 284, 23989-94