in the DNA Damage Response

The BRCA1/PALB2/BRCA2 complex tightly associates with chromatin. Previous report shows that most PALB2 tightly associates with the chromatin[1]. To study the BRCA1/PALB2/BRCA2 complex, we have examined BRCA1, PALB2 and BRCA2 in different cell lysate fractions with different salt concentration in the lysis buffer. As shown in Supplementary Figure S1A, when cells were lysed in the presence of 150 mM NaCl, most of PALB2 and about 50 % of BRCA1 and BRCA2 existed in the insoluble fraction together with chromatin. When cells were lysed with 300 mM NaCl or treated with MNase, chromatin-bound PALB2, BRCA1 and BRCA2 could be eluted into NP-40 soluble fractions (Supplementary Figure S1A). With a higher 420 mM NaCl treatment, most PALB2, BRCA1 and BRCA2 dissociated with chromatin (Supplementary Figure S1A). Since little PALB2 existed in the soluble fraction with 150 mM NaCl, little BRCA1/PALB2 complex was detected by co-IP and Western blot analysis (Supplementary Figure S1B). Since PALB2 can be eluted into the soluble fraction in the presence of 300 mM NaCl or MNase, the complex was readily observed when cells were lysed with 300 mM NaCl or treated with MNase (Supplementary Figure S1B). Although most of PALB2 and BRCA1 were in the soluble fraction with 420 mM NaCl treatment, we could only detect less BRCA1/PALB2 comple