Expression of hybrid class I genes of the major histocompatibility complex in mouse L cells

The class I genes of the major histocompatibility complex of the mouse can be divided into two categories: those encoding the transplantation antigens and those encoding the Qa and Tla antigens. The inbred BALB/c mouse has 28 potential Qɑ/Tlɑ genes. The sites of tissue expression, developmental regulation, and functions of these genes are virtually unknown. We have used the technique of exon shuffling to construct hybrid genes between each of three Qɑ region genes (Q5, Q7, and Q8) and two other class I genes (H-2L^d and Q6). The hybrid genes have been transfected into mouse L cells, in which intact transplantation antigen genes generally are expressed and in which intact Qɑ genes generally are not expressed. Analysis of expression of the hybrid gene constructs indicates that the 5' half of two of the Qɑ genes (Q5 and Q8) can readily be expressed in the context of a hybrid molecule, whereas the 3' half prevents cell-surface expression. The exon shuffling approach described here will be useful in characterizing Qɑ/Tlɑ genes and in identifying or producing new reagents to study the Qɑa/Tlɑa gene products, their tissue distribution, their developmental stages of expression, and, ultimately, their functions