Adapter protein implicated in the regulation of a large spectrum of both general and specialized signaling pathways. Binds to a large number of partners, usually by recognition of a phosphoserine or phosphothreonine motif. Binding generally results in the modulation of the activity of the binding partner. Negatively regulates the kinase activity of PDPK1. . This is the function of YWHAH (tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein eta, ENSG00000128245).