Updated project metadata. Identifying interaction partners and protein complex compositions for transcription factors (TFs) can produce valuable information on the mechanisms by which they regulate gene expression or are themselves regulated by signaling pathways in the cell. FAMA is a TF that is specifically expressed in the last stages of stomatal guard cell development in the epidermis of young leaves and other aerial tissues of higher plants. It is a master regulator of guard cell development and promotes terminal differentiation of the guard cell precursor by both activating and repressing hundreds of genes. How this is achieved mechanistically is still unclear. We therefore isolated putative FAMA interaction partners from young Arabidopsis seedlings expressing FAMA-CFP under the FAMA promoter using proteasome inhibitor treatment and formaldehyde crosslinking, followed by a classical co-immunoprecipitation mass spectrometry approach. Plants expressing nuclear GFP under a stomatal lineage specific promoter were used as controls. In two independent experiments with different crosslinking and immunoprecipitation conditions, we found ICE1, a known heterodimerization partner of FAMA, to be enriched in FAMA-CFP versus control samples. Other proteins with known transcriptional regulator or co-regulator function were not identified, presumably due to the low abundance of the bait protein. The interaction of FAMA with BRXL2, another regulator of guard cell development, which was detected in one experiment, is likely an artifact since BRXL2 does not localize to the nucleus under normal conditions.