Functions redundantly with TRAF1A in the regulation of plant immune response. Contributes to the turnover of the nucleotide-binding domain and leucine-rich repeat-containing (NB-LRR) immune receptors SNC1 and RPS2. May associate with an E3 ubiquitin-protein ligase complex, which modulates ubiquitination and subsequent degradation of NB-LRR immune sensors to maintain their homeostasis (PubMed:26867179). Functions redundantly with TRAF1A in the regulation of autophagosome formation. Required for SINAT1- and SINAT2-mediated ubiquitination and destabilization of ATG6. Functions as molecular adapter that helps to regulate autophagy by modulating ATG6 stability (PubMed:28351989). Forms homooligomers. Interacts with SNC1, RPS2 and CPR1/CPR30 (PubMed:26867179). Interacts with ATG6 (PubMed:28351989). Predominantly expressed in the cytoplasm (PubMed:26867179, PubMed:28351989). Associates with starvation-induced autophagosomes in continuous darkness (PubMed:28351989). No visible phenotype under normal growth conditions, but the double mutant plants traf1a and traf1b, or muse13 and muse14 are extremely dwarf when grown at room temperature.