Couples the p55 TNF-receptor (TNF-R55 / TNFR1) to neutral sphingomyelinase (N-SMASE). Specifically binds to the N-smase activation domain of TNF-R55. May regulate ceramide production by N- SMASE. This is the function of NSMAF (neutral sphingomyelinase activation associated factor, Ensembl gene identifier ENSG00000035681).