SMC1: Lysates

The ATM protein kinase phosphorylates SMC1 protein in cells exposed to genotoxins. Overexpression of a non-phosphorylatable mutant of SMC1 subjects a cell to a defective S phase checkpoint and decreased cell survival in response to genotoxic stress. In cells expressing this mutant, BRCA1 and Nbs1 are still phosphorylated, suggesting that SMC1 phosphorylation is downstream of these other phosphorylation events.