This family of proteins, found from plants to humans, is PRAT4 (A and B), a Protein Associated with Toll-like receptor 4. The Toll family of receptors - TLRs - plays an essential role in innate recognition of microbial products, the first line of defence against bacterial infection [1]. PRAT4A influences the subcellular distribution and the strength of TLR responses and alters the relative activity of each TLR. PRAT4B regulates TLR4 trafficking to the cell surface and the extent of its expression there [2][3]. TLR4 recognizes lipopolysaccharide (LPS), one of the most immuno-stimulatory glycolipids constituting the outer membrane of the Gram-negative bacteria. This family has also been described as a SAP-like MIR-interacting protein family.

1: A molecule that is associated with Toll-like receptor 4 and regulates its cell surface expression. Konno K, Wakabayashi Y, Akashi-Takamura S, Ishii T, Kobayashi M, Takahashi K, Kusumoto Y, Saitoh S, Yoshizawa Y, Miyake K; Biochem Biophys Res Commun. 2006;339:1076-1082. PMID:16338228

2: A protein associated with Toll-like receptor (TLR) 4 (PRAT4A) is required for TLR-dependent immune responses. Takahashi K, Shibata T, Akashi-Takamura S, Kiyokawa T, Wakabayashi Y, Tanimura N, Kobayashi T, Matsumoto F, Fukui R, Kouro T, Nagai Y, Takatsu K, Saitoh S, Miyake K; J Exp Med. 2007;204:2963-2976. PMID:17998391

3: A single base mutation in the PRAT4A gene reveals differential interaction of PRAT4A with Toll-like receptors. Kiyokawa T, Akashi-Takamura S, Shibata T, Matsumoto F, Nishitani C, Kuroki Y, Seto Y, Miyake K; Int Immunol. 2008;20:1407-1415. PMID:18780723