Characterization of a Q subregion gene in the murine major histocompatibility complex.

Abstract

We have used restriction enzyme digests, Southern blot analysis, and gene transfer experiments to identify a class I gene in the Q subregion of the murine major histocompatibility complex. By comparisons of class I genes from Q congeneic strains, five restriction fragment length polymorphisms were identified. Further studies of mutant (Qa-2-) and wild-type (Qa-

Structure and expression of genes encoding murine Qa-2 class I antigens.

“…It is likely that this structural difference is the direct cause of the change in Qa-2 phenotype from Qa-2+ to Qa-2-in BALB/cBy mice (13). A comparison between class I genes present in the Qa region of B10 and of Qa-2+ BALB/c (2) mouse strains reveals that a gene fusion probably occurred between a pair of ancestral BALB/c genes equivalent to B10 genes Q8 and Q9 (3).…”

“…2b) reveals the absence of a weakly hybridizing 3.5-kb Xba I fragment in BALB/cBy DNA, whereas probe 3 reveals the absence of a 3.7-kb Xba I fragment. A 3.7-kb Xba I fragment, which also hybridizes to a 3' class I gene probe and which is present only in DNA derived from Qa-2+ mouse strains, was described by Flaherty et al (13). Similarly, use ofprobe 1 reveals the loss of a 3.5-kb and a weakly hybridizing 4.8-kb Xba I fragment in BALB/cBy DNA (Fig.…”

Molecular studies of murine mutant BALB/c-H-2dm2 define a deletion of several class I genes including the entire H-2Ld gene.

“…Similar to the D region, a spontaneous deletion of class I genes in the Qa region has been noted (34); furthermore, the number of Qa region class I genes differs in the H-2d and H-2b Genetics: Rubocki et al Proc. Natl.…”

Molecular biology of the mouse Q region

“…Analyses of Balb/cBy, a spontaneously occurring Qa2-Balb/cY subline, indicated that at least part of the structural or regulatory gene controlling the Qa-2 antigen family resides on a 3.7 kb Xbal DNA fragment which is absent in all Qa-2-negative strains tested so far [12]. Mellor et al [ 13] could show that in this subline an unequal crossing-over had occurred between genes 6 and 7 (27.1) of Balb/cBy.…”

“…Mapping studies have uncovered large deletions in the Q region of some haplotypes, involving mostly the H-2K region homolo gous genes Q5 to Q9. It was postulated that in these strains the Q4 gene product might fulfill the Q region function [12]. The exten sive deletion found in the H-2 r strain makes it far more difficult to assign any essential role to the Q region [15].…”