Genes That Modify Expression of Major Urinary Proteins in Mice

Abstract

A survey of major urinary proteins (MUPs) from eight BALB/c mouse substrains by isoelectric focusing identified a common pattern with about 10 protein bands in males. One substrain, BALB/cJPt, differed in that it expressed two variant MUP patterns, designated 4.1^lo and null. To find the chromosomal location of the gene which determines the 4.1^lo phenotype, BALB/cJPt-MUP-4.1^lo was crossed with a wild-derived Mus musculus domesticus inbred strain (CLA) that expresses the common BALB/c MUP pattern. The F₁ phenotype revealed that the gene(s) controlling the MUP-4.1^lo trait was recessive. A restriction fragment polymorphism between these strains found with a MUP cDNA probe allowed us to establish that a gene determining the MUP-4.1^lo trait was not linked to the MUP structural genes on chromosome 4. Assays for other chromosomal marker loci revealed that a gene determining the MUP-4.1^lo trait, designated Mupm-1, was closely linked to Myc-1 on chromosome 15. To determine the genetic basis of the null trait, BALB/cJPt-MUP-null mice were crossed with BALB/cJPt-MUP-4.1^lo mice. A MUP restriction fragment polymorphism between these two lines was tightly linked to a gene or genes involved in determining the MUP-null phenotype. The two variant MUP phenotypes in BALB/cJ mice are determined by separate genes, one of which is located on chromosome 4 and the other on chromosome 15. The chromosomal location of Mupm-1 suggests that it produces a trans-acting factor which regulates MUP expression.