Positive regulator of basal resistance and of effector-triggered immunity specifically mediated by TIR-NB-LRR (TNL) resistance proteins. Disruption by bacterial effector of EDS1-TIR-NB-LRR resistance protein interactions constitutes the first step in resistance activation (PubMed:22158819). Acts redundantly with salicylic acid to regulate resistance gene-mediated signaling (PubMed:19578402). Triggers early plant defenses and hypersensitive response independently of PAD4, and then recruits PAD4 to potentiate plant defenses through the accumulation of salicylic acid (PubMed:11574472). Nuclear localization is essential for basal and TNL-conditioned immunity and for reprogramming defense gene expression, while cytoplasmic EDS1 is required to induce a complete immune response (PubMed:20617163). Heterodimerization with PAD4 and/or SGA101 is necessary for TNL-mediated effector-triggered immunity (PubMed:24331460). Contributes to nonhost resistance against E.amylovora (PubMed:22316300). Loss of EDS1-PAD4 interaction compromises basal but not TNL-triggered resistance (PubMed:21434927). Necessary for systemic acquired resistance (SAR) signal generation and perception (PubMed:24755512). Has no direct lipase activity (PubMed:16040633). Putative lipase activity is dispensable for immune functions (PubMed:24331460). Homodimer (PubMed:11574472, PubMed:22158819). Interacts with RPS4, RPS6, SNC1, SRFR1, AvrRps4 and HopA1 (PubMed:22158818, PubMed:22158819). Part of a nuclear complex made of EDS1, PAD4 and SAG101, that can be redirected to the cytoplasm in the presence of an extranuclear form of EDS1 (PubMed:22072959).Interacts (via N-terminus) with PAD4 (via N-terminus) (PubMed:11574472, PubMed:21434927, PubMed:22072959). Interacts (via N-terminus) with SAG101 (PubMed:16040633, PubMed:21434927, PubMed:22072959). EDS1-SAG101 and EDS1-PAD4 form separate complexes in pathogen-unchallenged cells (PubMed:16040633, PubMed:21434927). Part of a nuclear protein complex made of VICTR, PAD4 and EDS1 (PubMed:23275581). Interacts with VICTR (PubMed:23275581). Found in both the nucleus and diffuse in the cytosol when associated with PAD4, in the nucleus and in punctate spots in the cytoplasm when interacting with SRFR1, SNC1 or RPS4, only in the nucleus when associated with SAG101 and in the cytosol when it dimerizes. Found in the nucleus when interacting with VICTR and PAD4. Interacts with AvrRps4 and HopA1 effectors in microsomes. Up-regulated by salicylic acid or upon turnip crinkle virus or avirulent bacterial pathogen infection. No effect on RPS4-mediated resistance against avrRps4 bacteria, due to the redundancy with EDS1B.