Forms a complex with the serine/threonine kinase MEC1 which activates checkpoint signaling upon genotoxic stresses. The MEC1-LCD1 complex is recruited by the single-strand-binding protein complex RPA to DNA lesions in order to initiate the DNA repair by homologous recombination, after the MRX-complex and TEL1 are displaced. Required for the recruitment of MEC1 to DNA lesions, the activation of CHK1 and RAD53 kinases and phosphorylation of RAD9 in response to DNA damage. Required for cell growth and meiotic recombination. Forms a complex with MEC1. Localizes to nuclear DNA repair foci with other DNA repair proteins in response to DNA double strand breaks. The recruitment to DNA lesion sites requires the presence of the RPA complex on DNA. Phosphorylated by MEC1 in a cell cycle dependent manner and in response to DNA damage. Present with 606 molecules/cell in log phase SD medium.