GENOMIC ORGANIZATION AND CHROMOSOMAL LOCALIZATION OF THE HUMAN CASEINGENE FAMILY

Five yeast artificial chromosome (YAC) clones containing the human cas ein gene family were isolated and characterized to study the control m echanisms for the expression of these genes. Partial restriction analy sis in conjunction with the chromosomal fragmentation method and fluor escence in situ hybridization (FISH) analysis were performed to constr uct a detailed physical map of the casein gene family and to determine the chromosomal localization of these genes. The isolated YAC clones 748F3, 750D11, 882G11, 886B3 and 960D2 were 1.2 Mb, 860 kb, 800 kb 1.5 Mb and 1.5 Mb in size, respectively. The clones 748F3, 882G11, 886B3 and 960D2 contained the entire casein gene family, while the kappa-cas ein gene was absent in 750D11. The human alpha S1-, beta- and kappa-ca sein genes were found to be closely linked and arranged in the order a lpha S1-beta-kappa. The distance between alpha S1 and beta, and betwee n alpha S1 and kappa was approximately 10 and 300 kb, respectively. Th e beta-casein gene was oriented in the apposite direction to the alpha S1- and kappa-casein genes. The casein gene family was localized to c hromosome 4q21.1 by FISH analysis.