Fig. 1: BLM interacts with condensin II.

a SMC2 was identified by mass spectrometry in a co-immunoprecipitate of endogenous BLM from nuclear extracts of WT cells 3 h after release from G1/S arrest⁴. Select known BLM interacting proteins are shown for comparison. Isogenic BLM-KO cells were subjected to the same analysis and yielded zero hits for the listed proteins. Experiment was performed in triplicate. b Reciprocal co-immunoprecipitation of endogenous BLM and SMC2 from nuclear extracts of WT and BLM-KO cells 3 h after release from G1/S arrest. c, Proximity ligation assay (PLA) using antibodies against endogenous BLM and SMC2 in WT, BLM-COMP, and BLM-KO cells 3 h after release from G1/S arrest and quantification of BLM-SMC2 PLA foci/nucleus (WT, n = 111 nuclei; BLM-COMP, n = 103 nuclei; BLM-KO, n = 104 nuclei). Scale bars, 10 μM. Significance of difference between WT and BLM-COMP was determined by a Mann–Whitney test (ns, not significant). For additional PLA controls, see Supplementary Fig. S1a. d Five-subunit condensin I and II complexes (H, NCAPH; D2, NCAPD2; G, NCAPG; H2, NCAPH2; D3, NCAPD3; G2, NCAPG2). e Co-immunoprecipitation of endogenous BLM from whole-cell extracts of WT cells 3 h after release from G1/S arrest was probed with antibodies against condensin I and II subunits. Condensin subunits are color-coordinated with their respective condensin from (d). f Co-immunoprecipitation of endogenous NCAPH from whole-cell extracts of WT cells 3 h after release from G1/S arrest was probed with antibodies against condensin I and II subunits and BLM. g Co-immunoprecipitation of endogenous NCAPH2 from whole-cell extracts of WT cells 3 h after release from G1/S arrest was probed with antibodies against condensin I and II subunits and BLM.