PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator-1alpha) coactivators regulate adaptive gene expression in response to challenges such as cold exposure, fasting, or physical exercise to balance energy supply and demand. Transcription of a single PGC-1α gene produces different isoforms (e.g. PGC-1α1 to α4) with different biological functions. We aimed to characterize the nuclear interactome for each PGC-1α variant, in particular the transcription factors they bind to regulate gene expression. This was done by generating GST-fusions of all PGC-1a variants, expressed in an insect cell system. These were used to capture associated protein complexes from HeLa nuclear extracts.