High-resolution crystal structure of human Dim2/TXNL4B.

TXNL4A (thioredoxin-like 4A) is an essential protein conserved from yeast to humans and is a component of the pre-mRNA splicing machinery. TXNL4B was identified as a TXNL4-family protein that also interacts with Prp6, an integral component of the U4/U6·U5 tri-snRNP complex, and has been shown to function in pre-mRNA splicing. A crystal structure of TXNL4B was determined at 1.33 Å resolution and refined to an Rwork of 0.13 and an Rfree of 0.18 with one native dimer in the asymmetric unit. Residues 1-33 of TXNL4B have previously been reported to be responsible for its interaction with Prp6. However, this region extends to the β-sheet core of the thioredoxin-fold structure of TXNL4B. This suggests that the interpretation of the previously reported GST pull-down results without considering the structure and stability of TXNL4B is debatable.