MyD88 is a central signaling mediator of innate immunity, composed of the N-terminal death (DD) and C-terminal Toll/interleukin-1 receptor (TIR) domain linked by an intermediary (INT) domain. We showed that the N-terminal domain (NTD), composed of apparently unstructured 21 amino-acid residues, is involved in localization and clustering of MyD88 and is required for the efficient signaling, since the deletion mutant is unable to reconstitute MyD88-dependent signaling. Furthermore, we found that the NTD peptide interacts with phosphatidic acid, which potentiates MyD88-mediated signaling through TLRs. Propranolol and expression of lysophosphatidyl acid acyltransferase 1, which increase the level of phosphatidic acid augment cell activation via MyD88. Moreover, anchoring of MyD88 to the cell membrane augments signaling supporting the importance of membrane localization in MyD88-mediated signaling. (C) 2017 Elsevier Inc. All rights reserved.