Location of the gene for theta antigen in the mouse. III. The position of Thy-1 relative to Lap-1 and Mpi-1.

The position of the Thy-1 (theta cell surface antigen) locus on chromosome 9 of the mouse was determined relative to the biochemical markers Lap-1 (leucine arylaminopeptidase) and Mpi-1 (mannosephosphate isomerase). Four-point backcrosses using both male and female heterozygotes showed that the order of these loci is Lap-1--Thy-1--Mpi-1. By observing the segregation of alleles at the Mod-1 (cytoplasmic malic enzyme) locus, which is known to lie distal to these three markers, it was possible to show that Lap-1 is at the centromeric end of this gene group. The overall map for this portion of chromosome 9 as determined by these crosses is: Lap-1--5--Thy-1--7--Mpi-1--14--Mod-1.