CLONING OF THE REGION BETWEEN HLA-DMB AND LMP2 IN THE HUMAN MAJOR HISTOCOMPATIBILITY COMPLEX

The human MHC is one of the most extensively mapped regions of the hum an genome. Almost all of the class II region of the MHC has already be en cloned in cosmids but a gap remained between the DMB and LMP2 genes . Previously, screening of several complete cosmid libraries had faile d to bridge this gap, which may contain novel antigen processing or pr esentation genes. We constructed cosmid libraries from two different s ources in order to clone the region: (a) a library with fourfold cover age made from flow-sorted human chromosome 6 DNA and (b) a library der ived from a yeast artificial chromosome clone spanning the region. Usi ng this saturation approach, cosmid clones were eventually isolated ov er the region of interest. A single bacteriophage P1 clone was also ob tained spanning the region. The YAC, cosmid, and P1 physical maps were consistent and the distance between the DMB and LMP2 genes was measur ed as 70 kb. It is not clear why DMB to LMP2 is infrequently represent ed in cosmid libraries, but the clones that we have obtained will now enable us to search for new coding sequences.