HUMAN-IMMUNOGLOBULIN GENES OF THE CHI-TYPE THE LONG-RANGE MAP OF AN ORPHON-V(CHI) GENE REGION

As was previously shown by Zimmer et al. (EMBO J. 9, 1535-1542, 1990 and Biol. Chem. Hoppe-Seyler 371, 939 - 951, 1990), the so-called W regions comprising 11 V(chi) pseudogenes are located on the long arm of chromosome 2, very closely to the centromere. They are probably derived by a pericentric inversion and amplification events from gene regions of the chi locus, which is located on the short arm of chromosome 2 also very closely to the centromere. The restriction map of the W regions was now extended from the previous 1.2 Mb to 4.3 Mb and, at the same time, revised with respect to certain features. This was made possible by a new hybridization probe specific for the Wc region and by the improved resolution and extended range of pulsed field gel electrophoresis. On the basis of the long-range maps of the W regions and the chi locus the B(chi) genes of the chi locus have to be at least 2.5 Mb apart. This distance can be taken also as a minimal estimate for the size of the centromere DNA of chromosome 2; it is quite possible that the size is much larger.