This entry represents the cell division protein DedD from Enterobacteriaceae. DedD is an inner membrane protein that contributes to the cell constriction process during bacterial cytokinesis. It contains a C-terminal SPOR domain that may act as autonomous septal targeting determinant [, , ].
This entry includes death effector domain-containing proteins, DEDD and DEDD2. DEDD is a scaffold protein that directs CASP3 to certain substrates and facilitates their ordered degradation during apoptosis []. DEDD2 is involved in the regulation of nuclear events mediated by the extrinsic apoptosis pathway [].
Interferon-stimulated 20kDa exonuclease-like 2 (ISG20L2) is a 3' to 5' exoribonuclease involved in the processing of the 12 S precursor rRNA during ribosome biogenesis. Its N-terminal half promotes nucleolar localization and its C-terminal half contains an exonuclease domain responsible for the exoribonuclease activity. The exonuclease domain belongs to the DEDDh group of the DEDD superfamily [].
The poly(A)-specific nuclease (PAN) is a deadenylating enzyme involved in cytoplasmic mRNA turnover and consists of two subunits, PAN2 and PAN3, which form a conserved complex acting in the initial trimming of poly(A) tails, a process followed by the processive action of CCR4-NOT complex. PAN2 is the catalytic subunit and has two independent structural units, the N-terminal assembly unit which engages in a bipartite interaction with PAN3 dimers and the C-terminal catalytic unit [, , ]. The C-terminal unit contains the ubiquitin C-terminal hydrolase (UCH) domain, represented in this entry, and a RNase domain of the DEDD superfamily () [, ].
The major pathways of mRNA turnover in eukaryotes initiate with shortening of the poly(A) tail. CAF1 (also known as CCR4-associated factor 1) is an RNase of the DEDD superfamily, and a subunit of the CCR4-NOT complex that mediates 3' to 5' mRNA deadenylation [, ]. In yeast, CAF1 () is also known as POP2, and encodes a critical component of the major cytoplasmic deadenylase [, ]. It is required for normal mRNA deadenylation in vivoand localises to the cytoplasm. CAF1 copurifies with a CCR4-dependent poly(A)-specific exonuclease activity. The crystal structure of Saccharomyces cerevisiae POP2 has been resolved [].Some members of this family contain a single-stranded nucleic acid binding domain, R3H, such aspoly(A)-specific ribonuclease (PARN), which also contains an RRM domain []. PARN is only conserved in vertebrates and may be important in regulated deadenylation such as early developmentand DNA damage response [, ].
