DNA damage checkpoint protein required for chromosome break repair and for genomic stability during development. Interacts with ATR/mei-41. Highly expressed in the oocyte and nurse cells from stage 5 onward and in embryos prior to during nuclear division 14. Then, it decreases to background levels during interphase 14. Weakly or not expressed in stage embryos and imaginal disks. Expressed both maternally and zygotically. The EEXXXDDL motif is required for the interaction with ATR/mei-41. Belongs to the ATRIP family.