In plants, immunity is mediated by a cornucopia of receptor proteins. A crucial group of plant immune receptors belong to the family Nucleotide-Binding Leucine-Rich Repeats (NB-LRR). NB-LRRs act intracellularly to detect the presence of specific, pathogen-derived molecules termed effectors. Although our knowledge of plant NB-LRRs have advanced in the past decade, fundamental questions related to their function remain. Particularly, how are plant NB-LRRs regulated in the cell to ensure a timely defence response? In this thesis, we probe further into the mechanistic and molecular basis of plant NB-LRR function using the potato Rx1 as a model system. Introgressed from Solanum tuberosum spp. andigena, Rx1 confers defence against Potato Virus X (PVX) by gene-specific recognition of the viral coat protein. Specifically, we aimed to elucidate the roles of intra and intermolecular regulations underpinning Rx1 activity. Intramolecular regulation refers to constraints imposed by interactions between the subdomains that make up an NB-LRR receptor. Additionally, the activities of plant NB-LRRs are fine-tuned by interdomain interactions with accessory proteins belonging to the same complex. By addressing both objectives, we add to the mechanistic framework describing Rx1 function.