Substrate-recognition component of a DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complex required for cell cycle control (PubMed:20551172, PubMed:29779948). The DCX(TRPC4AP) complex specifically mediates the polyubiquitination and subsequent degradation of MYC as part of the DesCEND (destruction via C-end degrons) pathway (PubMed:20551172, PubMed:29779948). The DesCEND (destruction via C-end degrons) pathway recognizes a C-degron located at the extreme C terminus of target proteins, leading to their ubiquitination and degradation (PubMed:29779948). The DCX(TRPC4AP) complex specifically recognizes proteins with an arginine at the minus 3 position (R-3 motif) at the C-terminus, such as MYC, leading to their ubiquitination and degradation (PubMed:29779948). Also participates in the activation of NFKB1 in response to ligation of TNFRSF1A, possibly by linking TNFRSF1A to the IKK signalosome (By similarity). Involved in JNK activation via its interaction with TRAF2 (By similarity). Also involved in elevation of endoplasmic reticulum Ca(2+) storage reduction in response to CHRM1 (By similarity). Protein modification; protein ubiquitination. Component of the DCX(TRPC4AP) E3 ubiquitin ligase complex, at least composed of CUL4A, DDB1, TRPC4AP/TRUSS and RBX1 (PubMed:20551172, PubMed:19966799). Interacts with MYC (PubMed:20551172). Constitutively associated with TNFRSF1A (By similarity). Directly interacts with TRADD, TRAF2, CHUK, IKBKB and IKBKG (By similarity). Interacts with TRPC1, TRPC4 and TRPC5 (By similarity). (Microbial infection) Interacts with Hepatitis B virus (HBV) protein X; leading to prevent ubiquitination of TRPC4AP by SKP2. Phosphorylated by GSK3B; phosphorylation is required for ubiquitination. Ubiquitinated by a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase containing SKP2, leading to its degradation (PubMed:26038816). Phosphorylation by GSK3B is required for ubiquitination (PubMed:26038816).