This family was formerly known as DUF1000. The full-length, Txnl1, protein which is a probable component of the 26S proteasome, uses its C-terminal, PITH, domain to associate specifically with the 26S proteasome. PITH derives from proteasome-interacting thioredoxin domain.

1: Thioredoxin Txnl1/TRP32 is a redox active co-factor of the 26S proteasome. Andersen KM, Madsen L, Prag S, Johnsen AH, Semple CA, Hendil KB, Hartmann-Petersen R; 2009 Apr 6. [Epub ahead of print] PMID:19349277

2: Solution structure of At3g04780.1-des15, an Arabidopsis thaliana ortholog of the C-terminal domain of human thioredoxin-like protein. Song J, Tyler RC, Wrobel RL, Frederick RO, Vojtek FC, Jeon WB, Lee MS, Markley JL; Protein Sci. 2005;14:1059-1063. PMID:15741346