Expression of LY 6 D is induced at the surface of MCF10A cells by X ‐ray irradiation

In order to identify membrane proteins whose expression is induced by X ‐ray irradiation, we developed an antibody ( A b)‐directed strategy using a phage A b library. X ‐Ray‐irradiated cells were screened with a phage A b library in the presence of a large excess of polyclonal Abs prepared against membrane proteins that are commonly present at the surface of both X ‐ray‐irradiated and nonirradiated cells. After isolation of A b that bound only to X ‐ray‐irradiated cells, the antigen was identified using MS . Using this approach, we found that expression of LY 6D is induced in MCF 10 A cells by X ‐ray irradiation. The induction of LY 6 D expression is triggered through a pathway regulated by ATM , CHK 2 and p53. This method is a new A b‐directed proteomic strategy for analysis of membrane proteins, and is applicable to various biological phenomena in situations in which both target molecule‐expressing cells and nonexpressing cells are available.