By database searching with the sequence of the mouse Tlr4-associated protein Prat4a as query, Konno et al. (2006) identified a novel mouse sequence, which they designated Prat4b, and a human homolog . Using PCR-based techniques, they cloned mouse and human PRAT4B cDNAs from Ba/F3 and HEK293 cells, respectively. Mouse Prat4b has a deduced 27-amino acid signal peptide followed by a mature protein of 218 amino acids. Prat4b and Prat4a share 38% amino acid sequence identity and have 6 conserved cysteine residues in the mature protein. Northern blot analysis of mouse tissues detected ubiquitous expression of Prat4b, with highest expression in lung, spleen, thymus, and uterus.Prat4b associated with Tlr4 alone or with Tlr4/Md2, but did not associate with Md2 alone or with another Toll-like receptor, Tlr2.