This is a pseudokinase (PK) domain found in PAB-dependent poly(A)-specific ribonuclease subunit pan3. PAN3 proteins contain three prominent regions: an unstructured N-terminal region (N-term), a central PK domain, and a highly conserved C-terminal domain (C-term). The PAN3 PK domain has retained its ATP binding capacity, and this function is required for mRNA degradation in vivo. Analysis of Pan3 amino acids sequences show that, despite of retaining the general structural characteristics of protein kinases, the PK domain has substitutions in all the conserved motifs that are critical for kinase activity, such as in the catalytic VAIK and HRD motifs and in the Mg2+ binding DFG motif. However, the PAN3 PK domain has been shown to bind ATP. Furthermore, similar to other kinases, the ATP-binding site is located in the cleft between the N- and C-lobes of the kinase fold, however, the ATP-binding pocket is wider than that of typical kinases [3].

1: Structural basis for Pan3 binding to Pan2 and its function in mRNA recruitment and deadenylation. Wolf J, Valkov E, Allen MD, Meineke B, Gordiyenko Y, McLaughlin SH, Olsen TM, Robinson CV, Bycroft M, Stewart M, Passmore LA; EMBO J. 2014;33:1514-1526. PMID:24872509

2: An asymmetric PAN3 dimer recruits a single PAN2 exonuclease to mediate mRNA deadenylation and decay. Jonas S, Christie M, Peter D, Bhandari D, Loh B, Huntzinger E, Weichenrieder O, Izaurralde E; Nat Struct Mol Biol. 2014;21:599-608. PMID:24880343

3: Structure of the PAN3 pseudokinase reveals the basis for interactions with the PAN2 deadenylase and the GW182 proteins. Christie M, Boland A, Huntzinger E, Weichenrieder O, Izaurralde E; Mol Cell. 2013;51:360-373. PMID:23932717