Ubiquitin binding by a variant Jab1/MPN domain in the essential pre-mRNA splicing factor Prp8p

A Jab1/MPN domain near the C terminus of Prp8p. (A) The 2413-residue S. cerevisiae Prp8p protein carries a Jab1/MPN domain between amino acids 2178 and 2310. A recombinant C-terminal Prp8p fragment containing the Jab1/MPN domain (see below) is depicted underneath the full-length protein. (B) Alignment of the Jab1/MPN domains of several Prp8p orthologs. Residues identical to the human sequence are represented by dashes. The positions that correspond to the JAMM motif (E-X_n-H-X-H-X₇-S-X₂-D) in some other Jab1/MPN domains (Cope et al. 2002; Maytal-Kivity et al. 2002; Verma et al. 2002; Yao and Cohen 2002) are shaded in gray, and those JAMM motif residues that coordinate a Zn²⁺ ion (Tran et al. 2003; Ambroggio et al. 2004) are denoted with asterisks. A 65% Prp8 consensus and the representative Jab1/MPN domain from the NCBI database are aligned underneath the individual Prp8 sequences, and residues in the representative domain that match the Prp8 consensus are underlined. The site of a temperature-sensitive missense (I to N) mutation in S. cerevisiae prp8-28 (van Nues and Beggs 2001) is indicated by an arrow.