Ankara : The Department of Molecular Biology and Genetics and Institute of Engineering and Science, Bilkent Univ., 1997. Thesis (Master's) -- Bilkent University, 1997. Includes bibliographical references leaves 98-109. Breast cancer is known to be the most common cancer among women in the world. It is assumed that one in ten women will develop breast cancer till the age 80. Heredity is the major risk determinant in breast cancer. 30% of the women with breast cancer have a positive family history and 10% of women is defined to have high risk of early onset breast cancer who have multiple family members of breast and ovarian cancer. A novel breast cancer susceptibility gene, BRCA2 was confirmed to account more than 40% of the mutations in familial breast cancer patients. BRCA2 tumor supressor gene encodes a 3418 amino acid protein with little or no homology to other known proteins. There is no significant data concerning the cellular functions of BRCA2 and many facts about BRCA2 are waiting to be uncovered. The gaps in the knowledge about BRCA2 must be filled by generating new points of views and technical approaches. Such studies require the cloning of BRCA2 and the presence of purified protein products. In this study we cloned a fragment of exon 11 and exons 19 to 27 as 2 overlapping fragments. Since more than 80% of the mutations result in the loss of the C-terminal of the protein and produce cancer phenotype, we expressed and purified the extreme C-terminus of the BRCA2 protein. Sayan, Emre M.S.