LOCALIZATION OF 5 NEW LY49 GENES, INCLUDING 3 CLOSELY-RELATED TO LY49C

Nine genes belonging to the mouse Ly49 multigene family of natural kil ler cell receptors have been identified to date. Two of these genes, L y49h and i, are very closely related to the well characterized Ly49c g ene in the carbohydrate recognition domain. Here we show by Southern b lotting that at least two additional new sequences exist in C57BL/6 mi ce that are also closely related to Ly49c in the carbohydrate recognit ion domain. Furthermore, in contrast to Ly49a, extensive variation in the arrangement and number of Ly49c-related genes in different mouse s trains was observed. To characterize and localize the new Ly49c-relate d genes in C57BL/6 mice, we isolated and mapped genomic P1 clones hybr idizing to an Ly49C exon 7 probe. Locations and the relative order of all Ly49 genes found within the clones was determined. We also used po lymerase chain reaction to sequence exons 2, 4, and 7 from all genes. In this manner, we identified five new potential Ly49 genes which have been tentatively termed Ly49j-n. Ly49j, k, and n belong to the Ly49c- related subfamily, whereas Ly49l and Ly49m are most similar to Ly49d a nd g, respectively. Interestingly, the members of the Ly49c-related su bfamily are not clustered as a unit but are interspersed among other L y49 genes. These results illustrate the complex nature of the Ly49 gen e family and should aid in the understanding of functions, such as the mediation of hybrid resistance, in which Ly49c-related genes play a r ole.