Protocol for identifying the BZR1 interactome under starvation in Arabidopsis by metabolic stable isotope labeling quantitative IP-MS

Identification of interacting proteins, particularly those mediating protein degradation, remains technically challenging. The transcription factor BZR1 in Arabidopsis is activated by brassinosteroid (BR) signaling to promote plant growth and is degraded under starvation conditions to restrict growth and promote survival. Here, we present a protocol for identifying BZR1 interactors in plants under sugar starvation using ¹⁵N stable isotope labeling (SIL) followed by immunoprecipitation and quantitative mass spectrometry (IP-MS) analysis. This protocol has broad potential applications in studying the protein interactome. For complete details on the use and execution of this protocol, please refer to Zhang et al.¹.